For starters, that actually seemed like a reasonable puzzle to start off with, even in a game with more challenging puzzles. That dungeon will likely occur very early in the game for most players, considering the two quests that take you there are probably both given to the player within the first one or two hours of play. Taking that into consideration, it was a decent way to introduce the way some puzzles would function without blatantly telling the player "You need to pay attention to the environment!" Even games with tough puzzles, such as Braid, start off with relatively easy ones.
Also, not every game has to be a mental challenge. Sure, it is nice when those games come around, but let's face it, not many people went into Skyrim wanting to solve challenging puzzles to get through the dungeons. They wanted to explore a large world, and having a few easy puzzles along the way complements that feeling of exploration, as it makes the dungeon feel more important, without taking away from that core desire because you spent thirty minutes trying to figure out a challenging puzzle. In the end, it isn't that they are belittling our knowledge. It is that they want the puzzles to complement another purpose, not be mental challenges for the player to overcome. If you want games like those, then play Braid or any other game designed to specifically challenge the player's ability to solve puzzles. It isn't like we have a serious shortage of those with both classic games and indie titles.
And for the record, I'm normally one to criticize Skyrim, but I really don't think it was a good example to talk about belittling player intelligence based off of that puzzle.