Honestly, this actually makes me pretty sad. Those animations were badass, and I do feel like this made the Liches feel more like an actual credible threat.
I definitely agree that being an instakill that can't be revived from by a teammate was going pretty overboard and I do feel like that needs to change, but, perhaps ripping the system out wholesale is something of an overcorrection?
Personally, I would very much like an options menu setting (off by default, so folk like Rhaetalius won't jump all over it) allowing you to opt in for 'Kuva Demiliches', which would just re-enable the failure states - maybe even make them a little harder/smarter. This time though, instead of just being an unreviveable instakill, perhaps the awesome animation doing something like 35-50% of your hp as true damage would suffice - and then have us do a 'getting back up' animation that gives the lich time to quip about requiems and run away
This way, the sweet animations can stay in the game, liches can still feel like they could kick your ass, and no one is getting instagibbed just for having the gall to not be lucky with their parazon choices