I agree, too. We don't have a lot of MUPs here (3), but the only times I have been on them has been in the middle of the day, in the middle of the week when i am just going out for coffee, or on a cloudy-cold Sunday, when I thought there wouldn't be a lot of people. Both times there were fast riders, commuters, runners, strollers, dogs, kids. Even going slowly, I felt like I had to be on my guard so much, it's not very enjoyable. Especially, the Minuteman; it really is like a commuting road for bikes, and just like in all other forms of transportation, the closer you get to the city the more azzhole type riding you see.
2015 Trek Silque SSL
Specialized Oura
2011 Guru Praemio
Specialized Oura
2017 Specialized Ariel Sport