My problem is, auto-attacking creeps takes preference over Pressing Q and left clicking on the enemy!! (i.e. webshotting them). If arachna is auto attacking creeps, you cannot webshot the enemy without first moving away from the creeps (cancelling the auto-attack command), then webshotting him.
Surely, the command of webshotting the enemy hero (say you have to save teammate) should override the command of attacking a creep.
No that's not true. I've had this problem many times. Its a 2v1 in bottom lane, my teammate is attacking hammerstorm who's close to me. I have arachna who's auto attacking creeps. I'm repeatedly clicking Q and left clicking hammerstorm but it's not responding. I finally move Arachna away and then Q + left click him and the command executes as it should. I've used Arachna in over 60 games I can promise you this is the case.
Oh wait, were you saying that you have to cancel the creep attack command before you can webbed shot an enemy? It was programmed this way?
If it is, then why are we allowed to move from auto attacking enemy creeps to denying our own creeps, but we can't move from auto attacking enemy creeps to webbed shotting an enemy hero?
If it wasn't programmed this way, but you don't believe me, I implore you to try it out ingame. (Where an enemy is not on a screen, you're attacking an enemy creep, then he comes onto your screen and you can't webbed shot him until you move off the creep)
Tested. Had no problem.
It's possible I'm completely misunderstanding what you're trying to say, but from what I can tell it's human error, not mechanical.