Well I didn't actually mean that 'it' translated to 'o' so it'd be wrong to use it. I agree with you but sometimes you had better use 'o' in Turkish and sometimes you had better not. It depends on the circumstances, especially whether you point out something or not. That's why I actually wanted to omit it first but then decided that I should put 'o' to make the sentence sound more clear. Especially when there are ambiguities like 'kimin kırmızı tavası' without 'o' may also mean 'Whose red pan?' Either way I agree that 'o' is not necessary.
What I really meant above is that 'Kimin kırmızı tavası' and 'Kırmızı tava kimin' are slightly different structures although they may mean the same thing and 'Whose red pan is it' translates more to the former while the latter is the main translation. This might be because of the degree of flexibility that you have mentioned and then it's okay.