"Monstrous humanoids are not actually evil" is a rather common trope. Eberron did this. Several homebrewed campaigns do this, as well, and I'm pretty sure some D&D-inspired webcomics do this. And don't forget non-D&D fantasy settings! In the Elder Scrolls you have the orsimer (orcs) and dunmer (drow), and in World of Warcraft none of the monstrous humanoids are actually evil. Volo's Guide to Monsters, 5th Edition, even notes that monstrous humanoids may just be another race in your setting.