I actually think that the choice made MM7 a better game. I finished it for Good, but this way, I know that there's one whole branch that I didn't go through, and there's more pull to return .
(Also, generally, I think that this kind of exclusive choice makes games better, because you really need to choose and to steer the game in one of several mutually exclusive directions. Otherwise it would be just "maxing out", which I find less fun.
An example that you personally won't appreciate: In Heroes 3, you could build every building in every town, so, after some time, you always had ALL the units. In Heroes 4, building one dwelling in tiers 2-4 blocked the other, so you couldn't build it in that town anymore. I've been playing H4 for 15 years now and I still agonize over these choices, because it depends on the situation. However, in H3 there is no choice, after a couple of games you optimize your building, and it's not any fun anymore.)