This is probably an unpopular opinion here, but I think the proc set changes if balance right could be a significant boon for PVE. Ignore the PVP considerations here - which could have been addressed in different ways. These changes are being put forward because they help
Power Creep - a Problem in PVE that these changes address
In any MMO, every time new, better skills or gear are added, all the preceding content becomes a little bit easier. If not addressed this can make older content easy to the point of being boring and silly, and substantially shrink the pool of challenging end game content to enjoy (and the pool isn't very large yet in ESO).
Scads of new gear was added in the One Tamriel Update, along with 30 more CP. Another 30 CP are added with update 13. That means healing, tanking, DPSing all gets a bit easier. This rolls that back partially by nerfing around ~8% of DPS from proc based DPS builds. So clearing vMoL in 30 minutes is a little less doable. This game doesn't need to be dumbed down more. Challange is good, particularly for the end game.
Yes, but why this change
For one, because if this is done right it should increase the diversity in DPS builds. Right now the meta is heavily centred around high-crit proc builds. If this is done right, those builds will still be viable, but will be less dominant over alternative builds. Big if I know, but I think ZOS should have the benefit of the doubt.
But I spent so much time farming this gear
Welcome to MMOs. Any time new gear or content comes out, some old gear is bound to become obsolete. If you didn't realize that previously... you should now. If this is done right, these sets should still have some utility. ESO is far more generous to old gear than other peer MMOs too - the level cap hasn't been raised in ages, and sets like Valkyn Skoria and TBS that you got back when IC was first released are still useful today. That's pretty exceptional.
But PvP balance shouldn't drive PvE!
It isn't. This affects both by design. The reduction in PVE DPS is pretty obviously intended. Sorry, PVP isn't your scapegoat.