I'm not particularly fond of forced pitstops. IMO it adds nothing to racing, as you're not trying to conserve tires or fuel to get to your optimal pit window, you just pit when you feel like it. I don't know about other people, but on forced pit races, I turn the fueling all the way down, and the tire replacement threshold all the way up, so no work gets done to my car. At this point, it's more of a forced stop/go penalty than forced pit.
I would, however, like to see accelerated fuel/tire usage rather than forced pitting. That would put all the fun elements of pitting back in, and actually give you a reason to pit.