Current envelope modules are a bit inconvenient to use (or overly simplistic in implementation, but not in usage) especially when it comes to presenting that it does in UI, you can see it's actual shape after the fact as it plays out, but if you try to 'draw' it with modules like Points Curve, it's not very accurate looking.
It would be better if we had ADSR envelope module that has it's own GUI for both adjusting the envelope and displaying it at the same time, also would be better with curve points in the middle of the lines to bend them instead of using general linear/expo/log interpolation modes.
here's example (from Bitwig):
simple, hands-on and useful.
as for modes, it would be better to have additional simplified AD and AR modes, one without sustain or release at all, just attack and decay (so gate length is ignored), and the other without decay and sustain level, just attack and release curves, sustain is always at 100%. for certain scenarios these are more useful than whole ADSR.
Another type of Envelope module that would be useful is MSEG module, similar to Points Curve module, but with bend points between the lines and adjustable loop region.