I’m gonna try to keep this short and to the point.
If you’re complaining about the lion switch and how it feels wrong and out of character, it’s probably because you were listening to what they were telling you all this time and not looking at what they were actually showing you, and missed what these characters are really all about.
Lets start with Red:
The way to Red’s heart is through “self sacrifice” and “selflessness”
This is how Keith impresses her the first time, by ejecting himself into space and putting himself in danger to free her.
Then you can see their bond growing each time Keith gives something up for the team or risks himself in some way for it.
Like In the BOM dream, where he chooses to give up his knife.
That’s how Lance ends up in it now.
He gives up an important part of himself for the team.
He goes “It doesn’t matter if I’m not the best and will never prove myself good at anything or ever be worthy, the team is more important.”
And if you watch from the beginning of the series you’ll see hints of what Lance is actually all about and what’s his true strength
There’s actually a post about this going around I can’t find now, but Lance is the guy that would always do something risky to save his friends.
And despite how he always acts, he’s actually the most selfless guy on the team
This is also why Red doesn’t accept Allura and why it’s so hard for her, because she feels like she sacrifices EVERYTHING for the team and their mission.
But I think deep inside she knows there’s some stuff that she does for selfish reasons or things she still keeps a secret from the paladins.
Then we have Black:
The way to Black’s heart is through “Confidence” and “Trust”
This is why Shiro struggles with it so much in the first two seasons.
Shiro appears like a confident leader but inside he’s full of doubts.
He’s trying SO HARD to be the best leader he can be but he has so much fear in him all the time.
And sometimes he has confidence and he manages to bond with Black, and sometime he doesn’t and Zarkon snatches his control away. So he ends up being very unstable.
This is also why Black won’t accept him anymore, Shiro lost the confidence again (after Zarkon snatched his control again and teleported him back to Galra prison) he lost trust in the lion and trust in himself.
He’s full of fears again and Black doesn’t want a pilot like that. (no it’s not cause he’s a clone)
But who always had alot of confidence? Keith.
Keith seems like a hot head that doesn’t think about what he’s doing because what he suggests and does always seems insane.
But he only does these crazy things because he’s confident he can do them.
One of his first action in the show is driving off a cliff saying “Shut up and trust me”. And he makes it with no problem.
This is why he’s the perfect person for Black. He knows what he’s capable of, he has so much confidence he is able to face Zarkon all by himself! He almost has too much confidence at times haha
(He’s not a crazy hot head like Lance says, he’s just confident he can do stuff most people can’t, and he does.)
Now the way to Blue’s heart
is through something like “eagerness to prove themselves”
I’m just gonna quote what the show runners said about her:
“..but really the Blue Lion is kind of like the mother Lion. She looks for potential in a new pilot. Something to nurture and foster. And I think she saw that in Lance. She saw someone who needed confirmation that they were valuable to this team. Even though they didn’t believe it in themselves.”
That’s why she accepts Allura.
And that’s why it eventually will accept Shiro aswell, because now that Black won’t accept him and he has no part on the team but he really wants to be part of Voltron, she’ll see his eagerness and will help him. (And Allura will have to pilot the Castle sometimes)
Blue was also said to be the “Teamwork” lion.
And uniting people and making people work together is Shiro’s true strength.
Again, you can see from the first episode. He won’t shut up about teamwork.
Which is also a big part of leadership that Keith is struggling with and why they will eventually find perfect balance as the two main co leaders.
So the lion switch is not there to put them in their DOTU lions for the old fans, or promote one paladin over the other or ignore the bonding they had with their lions until now.
It’s to show that these characters are finally at a place where they stop trying to be who they think they need to be, and embracing their true selves and true strengths.
This is all very well thought through character development.