We already have two points of comparison in terms of mainstream shounen. Naruto and One Piece. Naruto empathsize every single viliain outside of asspull big boss villain, like every single one. To the point that thr final villain is litterally just an anti-hero. Humanising viliains doesn't during a conflict doesn't inherently make them better it makes the character deeper but if all you do is that it gets absurdly stupid unless you ground their objectives too. (Coming up with empathsiseabld reasons for mass murder rape and genocide gets stupid eventually). Azula is a good counts point as she's practically a One piece villain only near the end of two seasons worth of character development does she change. Even then it's not greatly.
I mean, no narrative technique, by itself, will improve or ruin any series. That's a bit of a caricature of what I'm saying. Kishimoto's work sucks because he's a pretty bad writer, and if he did have OP-esque villains, it wouldn't stop all the other flaws like the repetitiveness, the contrivances, the convoluted and unbelievable backstories, that make Naruto suck. It wouldn't have saved Naruto, but it wouldn't have improved it. Writing works as a collective, so humanizing villains is not an automatic pass to good writing. It needs the rest of the content around it to be good as well as having the execution of it to be good. What I am saying it is, however, is a plus. I've certainly never seen it be a negative.
Also, I'm not going to go into the Azula debate because this isn't the avatar thread, but I disagree with that allegation and the idea of Azula being OP-esque makes me throw up in my mouth a little.