Yeah, puzzles in TTG seem to be quite easier than some puzzles in LucasArts games.
I think it might have to do with their game release model. Chopping up games into episodes released every month more or less requires them to be solvable within the month, so that users buy the next episode when it comes out. In my experience, though, I haven't spent more than 2 days on any one episode (an average of 4-5 hours in total), and I've gone through TOMI, most of W&G and halfway through S&M1. I could definitely cope with a bit more complexity on at least some of the episodes.
On the other hand, having experienced the TOMI releases, I have a great deal of appreciation for all the community this release model encourages. It's great to have teasers for the episodes, to have forums, and to have extras (like the treasure hunt) that add so much to the game value. There's a lot more entertainment you get for the money (even when the puzzles aren't as hard as one would want). I say this even when I couldn't really play the treasure hunt due to incompatibilities with GNU/Linux.
In any case, I do agree with this thread and would love to see tougher puzzles in the games to come. I think the best way to deal with user satisfaction in this regard, though, was the way LucasArts and many others did. By including a choice of the level of complexity right when the game starts instead of having "some hints" and "overlaid text" enabled by default.