I think this card really kind of defines the game... in that if you play arena, your deck MUST be able to counter this, as dimensional shield is always strong. Always.
I see how this could make it look overpowered. But honestly, the same goes for creature damaging! Every deck needs some way of dealing with enemy creatures... so I suppose you could say that this is ok by that standard.
A lot of decks don't need a way to deal with creatures. Rushes for instance don't care.
That's... very rarely true. Having at least a minimal amount of cc gives you the edge over most non-cc rushes. It does slow you down vs domins/stalls, but it is a thing that you always have to keep in mind when you build your rush..