Geomancer has had many interpretations over the course of Final Fantasy's history. Compare FFV, where Geomancer produced random affects based on the current terrain, to FFVI where Mog could learn dances from various terrains but then could use them anywhere, to FFXI where Geomancer produced auras which, aside from technically being learned by going and visiting various locations in the world, don't have much to do with terrain at all.

If you are too attached to any one variant of Geomancer from over Final Fantasy's history, you'll likely be disappointed by however it's implemented in this game, because it most likely will not be the same. That doesn't mean that it's impossible for Geomancer to come to FFXIV; just that it won't much resemble previous incarnations of the job.

Blue Mage is much the same way, and you only need to visit any of the many Blue Mage threads to see how folks are polarized between insisting that it MUST have certain qualities that fit their image of a BLU, and others who feel that there's a lot of wiggle room that will still produce a job that feels BLUish.

As a point of interest, back long before they added GEO to the game, folks on the FFXI forums would speculate about the job. I noted that the game DOES keep track of the different kinds of terrain a character is standing on: When you're in water, your footsteps make splashing sound. Mud makes squelching sounds. Snow makes crunching sounds. Forcefields (such as in Tu'lia) make electronic pinging sounds. And so on. I thought it would have been neat to have jobs with different effects depending on where the GEO was standing. What we wound up with was very different, but no less valid an interpretation of the job. The same would be true for FFXIV.