No offense to you personally, but this is a big misconception about the first one that drives me crazy to hear.
The only way to get the bad ending is kill QUITE a lot of people. That's it. It doesn't enforce anything on you, in fact you can kill several people every single mission and still be fine. When you factor in the powers and all the environmental stuff you have TONS of options that don't involve killing.
It certainly cuts off some of the tools from being used frequently, but you can absolutely engage in some deadly violence and still be fine.
While I don't think the system is THAT good (certainly a lot of room for improvement and clearer choices) it's not this totally punishing and strict set of guidelines that people seem to think it is.