There are plenty of trademarks I think are questionable, particularly ones where a company will trademark a commonly used word for their product (Windows and Office spring to mind, though I'm not anti-MS), but I agree that trademarks are the most sensible of the major IP categories.

Also just practically speaking it is much easier and safer to research trademarks ahead of time and if things still go wrong it is easier to just rename something (especially if you're in an early stage) if you run into a conflict than it is to try to recreate whatever your product is from scratch as you would if you ran into a submarine patent.