I wouldn't say anime has become stagnant like AT ALL. On the contrary I find myself watching more anime now than 5 years ago.
About 3D anime, Ajin was awesome and Houseki no Kuni was a masterpiece, so I don't think there is a correlation between 3D animation and overall quality. (The 3D in Inuyashiki is fugly tho)
The industry is just not sustainable for traditional 2D anymore. Every now and then you get animators literally dying from overworking.

But yeah whats with these bots in your comments lol