You have 3 other characters, grenades, barrels, arrows, enemies and the almost excessive prevalence of environmental surfaced, to rely on for surfaces already.
On it's own it's a skill that could be interesting, but as part of that specific kit it's just superfluous and misplaced.
You can play without other characters, or depart from the party to go do competitive questing. Grenades, barrels, arrows and enemies make surfaces which are MUCH bigger, and aren't people already complaining about the entire screen already blowing up in every big fight?
I think Dimensional Bolt is fine as a part of the Summoner's Kit. The surface it produces is about as small as surfaces get. If you don't want it to make everything blow up, you can find an empty space out of the way with no existing surface.
If you don't like the surface you get (i.e. fire), them's the breaks, try again next turn. You can always summon wood for physical damage.
