Summit: For reasons unknown to anybody but Todd, Bethesda likes to put such balance breaking stuff in their games.
P.S. Speechcraft. The most stupid minigame known to man.
Yet nobody forces any gamer to actually use those. Neither the skeleton key nor the stealth armor. Anyone who does = suit yourself, no reason to complain, at least in my book.
Oh, and those who still do: maybe consider "roleplaying" and saying no to stuff that doesn't fit, instead of complaining? :p
... and for Speechcraft in Oblivion... yes it wasn't a good solution. However, compared to the one in Morrowind (which was way more open for abusing), it was a step forward at that time.