Yes, it is easier to open a lock as your lockpicking skill increases. It changes the "sweet spot" for opening the lock to a larger area. However, I, as a player, can have my character open any lock in the game at a lock picking skill of 15 and that is what is wrong with the mini game.
So then you, as a player, are very good at opening locks. I don't really see it as something of a flaw with the mini-game concept. Sure it could use a little more juice in the sense of making it more difficult as a player to open locks if you don't have the appropriate skill level/gear, but the concept is sound and is the way of modern gaming where we're no longer limited by technology (In my opinion).
Combat in Morrowind was like this. Landing a sword hit and dealing out damage was only dependent on your characters' skills in the weapon used. That is why you could swing away with a sword in Morrowind at low levels and barely land any hits. They tried to do this with a hit box in this game. However, what I am talking about is the minigame removes any and all needs to work on a lockpicking skill if the player can overcome the character's limitations. That is not Role Playing.
You could just as easily argue that it was absurd to visually land tons of hits on an opponent and have them just miss because of a dice roll and that it is not role playing and just immersion breaking. That's the beauty of Role Playing, it can be defined in so many different ways. Toodleoo.