The Herald experience...
unless you place energy gain in all weapons /stances/traitlines you will end up feeling like you NEED to use that specific weapon/stance/trait cause it,and only it gives you more energy which is always usefull.. and that creates a problem with “forced” staples for a build.
lets say we get more utilities per legendary stance. instead of 3 we get 4 or 6. we will still only be able to use 3 per stance and the 3 will be the ones that are most useful. The current neglected stance skills will still be neglected, just replaced by the new ones that are slightly better. Just buff the neglected stance skills instead, even so slightly so people can use it now and then without worrying if they just wasted 10-30 energy on nothing useful at all.
Cooldown on skills prevents possible high damage bursts as seen via thieves that will run you down to 0 energy.. twice for each stance. This will result in you just standing there auto attacking or trying to run away somehow..
You mentioned thieves? Imagine a burst damage thief with no stealth and no initiation regeneration as well as “disabled utility and healing skills for at least 5 seconds when initiation goes down to 0”
Elementalists that are tempests have the ability to overcharge their attunements once they stay in them for a while. Perhaps we get a similar new elite specialization next expansion.
That, or a special core trait from a non specific stance traitline that grants us such effects across all stances. Even something small such as “gain 10 condition every 2 seconds up to 100 condition damage while you are invoking Mallyx”