I would be more content with swap in attacks (and swap in moves in general) if I knew when my opponent could or couldn’t use them. There’s no way of knowing whether or not your opponent drew their rhino, so you always have to play assuming that they have one, making them disproportionately dominating in the meta. Rhino isn’t even especially strong outside of this move, but the surprise factor on swap in attacks is such an asset that it becomes a must-play.
I don’t think an attack nerf is enough to fix the problem here. It doesn’t even matter how much damage they do: if you’re at 1500 hp or 1 hp, if you outspeed your opponent and are about to finish them off, only to have them switch to a swap-in attacker and kill you instead, you still feel robbed either way. Not to mention that some swap in abilities are very strong despite doing 0 damage (like swap in slow). I think there should be some way of knowing what swap in attacks your opponent has so you can plan around them (like seeing one another’s teams at the start of the match). You can click on your opponents creature and see every possible move they can make - EXCEPT for attacks they can use by swapping to something else (i.e. swap in attacks). If you were informed on whether or not a swap in attacks was an option for your opponent, you could plan around it like any other move, and I don’t think they would feel quite so unfair.