I'm really against the whole "it's too hard so you can't even try" thing, so no I'm not in favor of that. however I do see an issue with someone simply saving and reloading till they get it right. So maybe make the lockpick minigame so that you can make it pretty much impossible with too low a skilllevel
They always put a non-minigame-route for their lock-picking action, so if you chose that way, you are not blocked by the impossible-to-win minigame.
Thus with save and reload, you can do the job.
So, the too-hard-to-pick seems mandatory.