Those other parks may inflate those stats a bit. Coors Field turns Vinny Castilla into an All-Star. Todd Helton won't sniff the Hall of Fame, nor should he. I'm a bit more sympathetic to Larry Walker as he could hit anywhere, but he was hurt all the time.
I'd say baseball is the hardest major sport to stay with one team. If your team cuts ties with you, and you have even a shred of talent left, you'll have a team that can find a spot for you, whether it be platoon batter or a situational pitcher. Also the sport allows you to play longer. NBA/NFL requires lots of running/jumping/contact which blows when you get older, plus in the NFL when you're 30, unless you are a kicker or QB teams want nothing to do with you.
MLB you get to stand around in the field or sit in the dugout for prolonged periods of time. Easier life.