Well if you haven't seen it, then it must never happen.
With which option does WotC run at the greatest chance of losing satisfied customers?
Not saying that it does not happen I have read people complaining about it here enough so it must happen. I am saying that in the 30 years I have been playing I have never seen it come up in a game as an issue.
I view it as a player issue not a design issue and the people I play with have the same view. A spell like knock is in the game so that the party can operate without a rogue and while it can be used to out shine the rogue that was not why it was put in the game.
I will not deny that certain spells can really make the wizard hard to deal with take fly and improved invisibility they can really ruin a DMs day. Which is why I think making those spells harder to cast is a great idea.
I think the direction they took in 4e was not the way to fix this issue. It is one of the main reasons we only played a few sessions of it before saying nope hate it not for us and went back to 3E and then to Pathfinder.