In general, I think a feat that simply causes it to be a class skill or changes the cost is not a well-designed feat (it could easily be superceded by multiclassing or changing to a prestige class). (Yes, I think MWP is a problematic feat, too).
In Star Wars, the feat requires one or more ranks in a skill, which is not already a class skill, and makes it a class skill as well as granting a +2 bonus. I think that works pretty well, but seems overly restrictive.
Incidentally, I've noticed that a number of players like to take Able Learner or the aforementioned feats at 1st level, thinking to get a break on your 1st level skill points. That won't work, unless the feat is granted by a class, as selecting a feat is a later step. Ironically, it's usually a better idea to wait until second level to invest ranks in a new class skill gained this way, unless it can only be used trained, or you want to keep it maxed and have very few skill ranks.