If it is an activity you're undertaking with your friends, then DM declarations are generally a bad idea.
I don't see this; do people have really fragile friendships these days? I blame the education system!

I find that something like this kind of negotiation exercise is necessary when playing with my 3 year old son Bill, because he does not have the maturity to play something which does not exactly fit his preferences, but I have never found it necessary when gaming with adults.