Yeah, you have to discuss your issues with the additions. If they are non-technical then you can make up some story about the world exploding if they go through with it...

...I'm a non-technical co-founder and I DO micromanage, but I keep an open mind if my programmer says it is more difficult, harder to implement etc. We have a good relationship with that type of stuff. Marketing/business people have reasons for where they put buttons etc., but you need to get on the same page with him about projects that can't be added.