On-use trinkets undeniably give u a boost, but if you're going to apply this methodology it needs to be across all the contributing factors, not just PvP trinkets. Don't try and hide this issue with a simple fix that you believe can be remedied by nerfing "1 of 3+" contributing cooldowns that are all simultaneously linked into the same macro. I know ya'll aren't that naive.
Also, I really think you owe a trinket refund to the people who have bought the on-use / upgraded it. I'm sure many people bought it specifically because of the "controllable burst" it offers and since your generally nerfing that aspect of it, players can more easily see that it offers less stats overall than their on-proc counterparts.
Another thing. Because of this change, people playing human are going to have just as much if not more burst potential on openers. Because of the high proc rate on the PvP proc trinket equivalents (smart) people will end up double stacking them (malev with upgraded JP equivalent) and be essentially getting MORE stats that what would be available from Use + Proc (that is assuming you hold true to what you say in that you will be cutting the value and cd in half).
So, for those that do this, not only are their openers going to be even more bursty because they will be trading more stats for a little less control, but there will also be more rng involved, and I thought RNG was something you were trying to stray away from. I'm not entirely opposed to it, I just thought that was a stance you made.
Ultimately this is just going to make the PvP trinket fairly unattractive for anyone that can do basic math. It removes a lot of the creativity from having different options for PvP trinkets. I believe this kind of "homogenization" is one of the things that is making the game harder to balance and ultimately less interesting.
This game was great and I fell in love with it for a reason. I know much of the PvP community is very "group think" oriented and will just repeat what ever the "better players are saying," but I know ya'll are smarter than that. Ghostcrawler himself says that they don't always base things around "top parses or logs" because often times people can be very narrowminded. There are many things that I don't agree with but he has a very good point.
People need to have alternative opportunities to shine. Please stop moving in the direction of taking more opportunities away and address the core issue. I know ya'll are intelligent enough to realize this isn't a "real" fix.