I had issues with taking the "mean" route early on, but eventually one realizes that most paths end up in generally the same area. You can't really do anything to "break" the game, per say -- no matter what, you find yourself at the same endpoint.
As for what you're saying... If you want a successful group of party members, well, you're going to have to find NPCs that mesh with that playstyle. I assume you still have Morrigan around, and unlocking the specialization will give you the option to make her a Spirit Healer if you don't want to do it yourself. That, or just be prepared to suck down a lot of health poultices. There are ways around Wynne, and if you're being evil to role play the game, would you really want her shaking her finger at you the whole time anyway?
I feel there is a satisfactory balance in this game of NPCs to accommodate every RP style. For Wynne, there is Morrigan. For Alistair, there is Oghren. For Leliana, there is Zevran. Any combination of NPCs can get through the game -- it's just up to you how you use their abilities to make it happen.
