No its not; when you do it because you're trying to talk to the vendor whos moving around his object and accidentally pick an object....or moving around town for that matter
If you do it on purpose, that's your thing...and the game allows you to do that which is nice...
but when the game control's mechanism force you into this mistake...it is plane stupid
I agree this would be a good improvement. I find some NPC wander too fast and you have to click around them trying to engage in conversation and pick up something by mistake.
It isn't getting caught stealing that is the issue - it is the UI pushing you into an unintended action. Perhaps my mouse is crap, or perhaps I am not very dexterous, but generally this isn't a game where that matters and it is a bit annoying when it does.