Nice post and I agree with it. Currently the PSI waves don't feel natural, but rather forced.
I would like a system in which I can cast at least one wave, once every [insert random time interval here]. In other words, here's what I'd love to have:
- no more shared cooldown between PSI waves;
- increase the duration;
- either impose a limit on the number of PSI waves active at any one time, or simply allow any number but make them last X seconds with 2*X cooldown;
- if the first way is chosen, make sure we need to make hard choices regarding which of them to use and also make the cooldown equal to the duration and disallow using the same wave multiple times (because probably except for people at the late game, most of us will use as many waves for power regen as possible);
- if the second way is chosen, disallow using the same wave multiple times but increase their effects by at least 50%.

Another idea would be to also make them instant spells (i.e. can cast them without triggering a global cooldown nor stopping your character in place).
PSI Waves should be "fire and forget" spells in my opinion, instead of having to constantly watch the duration and/or forcing you to not use other spells for quite a bit of time (since you need to keep refreshing them if you want to have 2-3 up). Not having a way to see the actual duration/cooldown numbers on buffs/abilities (without hovering over) doesn't help either.