Fair enough, my language was sloppy.
What I was trying to say is: it would be interesting if the choice of favored terrain granted an ability that was useful in all terrains, in addition to expanded utility limited to the chosen terrain. For example, Favored Terrain: Mountain granting a climb speed, as well as all that stuff about tracking at higher speed, etc. etc.
I like this, as it is similar to the Druid of the Land. Land druids get bonus spells that are associated with, or particularly useful in, their home terrain (e.g. spider climb in mountains, water breathing on the coast, or blur in the desert), but they're pretty useful out of it as well.