No that's wrong the next waves doesn't change that you can be more efficient in current situation by using better tactics or even some strategy.
You are using tactics for influencing the current fight but also the whole fight. And no, new strong waves won't destroy this and will just force you define new tactics.
You continue think that the only tactics is about planing something from begin to end of fights and that's very wrong, in any game, even in DAO static fights that have no reinforcement, no hidden enemies, no summoning.
EDIT: But I do agree the go comparison isn't exact. But I wonder if you really play chess or go more than for a casual try. Even after years of training and practice, you'll see how opponents can be sometime unpredictable. And that more than once in a game, even a tactic started will have to be changed because you get surprised. Also what you are saying about static fights and tactics is a bit like saying that there's no tactic in go because you can't plan safely a tactic from begin to end of game and nobody can do that, in chess (I know quite better) nor go (that I played only a bit with local level players).
Another point is there isn't constant waves, and in between waves there's a large place for a lot of tactics, and ok some could destroy a current one, but it's a fast game you better pause a lot, and if this happen, notice it and plan something else is fully a tactical analyze. In that sense waves tend make me think more about tactics and I never bother if some will come or not.
Also last point, for some fights, yeah a strong wave can destroy all including making you lost a fight. But that's for the best fights, most often it's more the surprise that made you lost, and anyway restart such of the best fights knowing more about waves coming is a tactical pleasure, well for players enjoying tactics.
And it's not for so many fights, plus quite often you can push longer the fights to see more what's coming next.