I don't think I have ever had a forecaddie in my life and I don't have much interest in them or real caddies. However, if a club insists one needs to belly up or leave the bar.
So far as being a member of a club which requires visitors to use them, I guess it depends on how much the club needs visitor fees. I do think JakaB is right in that decent caddies will be more cognizant of what is happening in the group behind and encourage faster play or encourage the guys to let the members through. On the maintenance side, I haven't seen anything to suggest visitors leave courses in poor condition, but then I play most of my golf in the UK and I think in general golfers are more respectful of courses than in then US. That doesn't mean I don't often repair more than one pitch mark on greens, but it normally isn't that bad.
Ciao