I think I've finally found some words to express my long-time irritation with how bards are typically represented and implemented in RPGs.
The most common phrase I've seen to describe the Bard class, in any game, is "Jack of all trades, master of none."
In other words, the bard is seen as a "filthy casual," someone who dips their toes into every skill-pool enough to be a crappy second-choice for any role, but never good enough to actually substitute for a missing role - at least not without optimizing for that role to the point they may as well have gone with a different class - and not the person you'd choose to group with for something truly difficult. They're seen as lacking the focus, or the skill, or the dedication to become truly good at anything.
This description has always bugged me. I love bards - I consider myself to be one, so I will admit to personal bias - but my image of a bard is cut from a different cloth, I suppose. I don't think of the tavern-crawling, bar-room brawling hedonist that seems most heavily represented in D&D tropes. My model for bards and bardic behavior came from the Harpers of Anne McCaffrey's Pern series, and I've spent a good part of my life internalizing that model.
So the idea that a bard is just a lesser-skilled, second-rate support class that has nothing to offer which another class (support or otherwise) can't do at least as well if not better, has always grated.
Focusing on this "master of none" concept as a limitation ignores the strength that a diversity of knowledge provides, and reinforces impostor syndrome with the reminder that, no matter what you do, you'll never actually be *good* at X, only tolerable. You'll never be as knowledgeable about Y as someone else. In short, there's always going to be somebody better than you at anything, so the message becomes "don't feel too proud or certain of your abilities."
So what is the strength that comes from a broad, if at times shallow pool of knowledge?
A bard may not know as much about a particular topic as a specialist, but they probably know the basics. The specialist can talk about their work, and the bard can - to a point - follow along, ask questions, possibly serve as a "rubber duck" to bounce ideas off of and catch simple mistakes that may have been overlooked.
A bard is the writer who researches various topics to bring realism to their work, because you "write what you know." Why does the bard know about metallurgy? Because they once wrote an epic about a legendary dwarven crafter, and it would not do to get the details wrong.
A bard is the advisor or counselor you go to with your problems, because their breadth of experience means they may have heard of more ideas to solve them - there's more than just a hammer in a bard's toolbox, so not every problem looks like a nail - and because they can empathize with and understand your problems, and you, better than anyone else. You talk to the bard because they make you feel seen and heard and understood, and even cared about.
(Side Rant: This is where the Horny Bard/"Seduce All The Things" trope misses the point, I think. Any character can be physically attractive, and most are - regardless of Charisma score. But the bard knows how to be a compassionate listener, how to connect with people in a way that many simply aren't used to experiencing. Sure, some might take advantage of this, but that's a matter of character personality rather than character class.
People would be rightly outraged if a spellcasting character used Charm Person to achieve the same results, even though mechanically there's no real difference. We can only be ok with the Bard doing this if we assume some level of agency and consent on the part of the NPC, something that is generally glossed over when this trope comes into play.)
A bard is the negotiator you bring in for a difficult situation, because they can read people, they understand how people think and can influence them, because they've met and studied so many people. Their knowledge of current events, politics, trade routes, agricultural practices, or even languages could be the deciding factor in getting to an agreement, whether that's just a better reward for the party or talking someone into releasing a hostage.
A bard is the person who is well aware of the fact their own skills are limited, but also well aware of the skills of those around them. The bard knows what their party members can do individually, as well as how their talents can work together. They know when to push, and when to retreat and try again later. The bard is the strategist, the mastermind.
A bard is a leader, but not the kind that takes credit for leading. The bard whispers the words that inspire an idea in the mind of the one who "looks the part" of a leader - the heroic, chiseled champion; the head that wears the crown; the peasant revolutionary. When a bard is praised, they are lauded for their skill in lifting others up, making them larger-than-life, encouraging them to be better than they think themselves to be. As part of a group, the bard is both the glue that holds the party together and the one who pushes each individual toward improvement and growth: the Team Mom, the Space Dad.
Yes, they can also be the obvious leader, or "face" of the group, but the bard can be just as effective behind the curtain. Some even prefer to be the stage manager, rather than the performer; the power behind the throne; the second-in-command, because they don't see themself as the leader type. But in their element, when they're not trying to be the leader, they inspire others to follow regardless.
How do you represent this, mechanically? The Inspire songs from 3rd Edition weren't a bad idea, but overall a person chose Bard for the aesthetic, not the mechanics. Other classes had spells that could duplicate the effects a Bard could achieve with their songs.
You have to make the mechanical advantage to having a Bard in the group better than what could be achieved by doubling up on another class. You have to make their inclusion propel the party as a whole into something greater than the sum of its parts, including the Bard. No, a Bard shouldn't be mechanically necessary but having one should make enough of a difference that it's always desirable - even to the point that not having one can feel like a penalty - and that can't happen when everything they can do can be reproduced by other classes, or when the benefit they do provide is considered a minor bonus at best.
But it seems clear to me that a Bard's abilities should always be enhanced by having greater knowledge, even if the benefit of that knowledge isn't immediately obvious to the given situation. Not enough to replace having first-hand skill, but perhaps similar to how skill synergies worked in 3rd edition, except that a Bard's Knowledge or Lore skill would synergize with every other non-lore skill, and even influence the benefits they grant to others through Inspiration.
If we're going to insist on the Jack-of-all-trades as a basis for the class, we need to get rid of the "master of none" appendix. The bard is a master at interpersonal relationships and of lore, of inspiring others to be the best versions of themselves, and of leading from the rear.