Even in oblivion, I used to see people just spamming auto pick.. Is the mini game THAT hard?
Actually for me it's because it's too easy. Both in Oblivion and Skyrim, the mini-game is so easy that I can get through master locks without trying when I'm low level. And given how much Skyrim loves to rain lockpicks on you, I never have any trouble getting through locks.
At least with Oblivion, the Auto Attempt gave some semblance of a meaningful character skill. Harder locks would chew through your lockpick stash like nothing if you were low level, thus required managing your lockpicks. Attempting a hard lock before the character's good enough would risk depleting your lockpicks, so you wouldn't be able to open any lock thereafter if you failed, unless you're lucky enough to run across some more (and even then, you could still fail with those new lockpicks).
In Skyrim there's no such thing, so once you, the player, get the hang of the mini game, the skill becomes useless and it's based all on you. If you as a player can't fail, there's never any risk to your character for trying. You can't play a thief taking chances because the character's skill level means nothing as long as you, the player, can get through the lock.