No, Skyrim is a horrible place filled with horrible people.
Also, if you pay attention to the quest dialogue, half the kills aren't for money. The point of the questline is to bring the DB back into it's former glory. This is done by killing a high profile "impenetrable" target (emperor.)
My final thoughts.
1. The bride deserved it. She was an imperial and that is enough reason for me.
2. In regards to your dislike of killing innocent people...
If you can't handle the heat, stay out of the kitchen.
It is a horrible place filled with horrible people, so why should I contribute to it? The bride in solitude if you talk to her seems pretty neutral on imperials/stormcloaks, she isn't prejudice or why else would she be marrying into a stormcloak family? I think she was just born into an imperial family, I don't think that justifies her death. I have no problem hacking dozens of imperial/thalmor/bandit's..etc's heads off if they provoke me.
I haven't completed the DB questline but I disagree, I'm sure it's all about money. The only reason astrid wants the brotherhood restored to it's former "glory" (whatever they think that means) is so they can be more feared/recognized and thus get more contracts. Why would I want to help restore that riff-raff excuse for a cult anyway? If I want to kill the emperor id do it for myself, I don't worship anyone especially a deity as repulsive as this "Sithis".
Don't get me wrong, I dig the whole assassin thing, I just simply don't like the dark brotherhood or what they stand for. I'm playing a dude with the soul of a motha ferkin dragon
I don't need to take orders from some bag of bones in a box (or flesh for that matter), but maybe you're the submissive type, I could see how Astrid could be appealing in that aspect.
Anyways, I was just curious how many other people chose the same route I did, as it seems the lot less frequent path, I'm just glad Bethesda didn't force me to join that crappy cult and let me destroy them instead.