I think construct 2 needs to allow one to be able to group instance variables.
Group Constants could contain acceleration, deceleration, jump power. You would access these in the event sheets by... SomeObject.Constants.acceleration.
This isn't needed for small scale projects but as soon as you need more complex behaviors you need tons and tons of instance variables. I used to just make multiple objects to store different info (like playerState and playerMath) - but given constructs limitations in polymorphism you can't simply scale a project built like that...
anyway... it would help with organization. My hunch is that those of you who disagree either haven't attempted anything grand in scale or found a better way to organize data in construct 2 (in which case I am all ears!)