Couple of reasons:
1. have been on the 55 and really love the boat.
2. I currently am 52ft and its next to impossible to find slip space, regardless or price, it just simply does not exist. They rent slips in 5ft increments, meaning a person wanting room for a 52ft is same as person looking for 55ft, I am currently in a 55ft slip.
3. Slip space is really really hard to find over 50ft, under 50ft no problem, over 50ft good luck.
4. Slip space is really hard to find.
5. Have run into several 60+ ft boats, and they say they can't find slip space at all anywhere.
Please keep in mind my recent experience has been Maryland down to Florida, am sure its probably different for those on the West Coast. Truthfully IF I was looking for a boat, would try to find a 48ft boat just so I wouldn't have to fight to find a place to park.
When I was looking for a marina, bet I called 200 marina's if I called one, no luck. Only way I got the space I'm in now, just happen to call them and they said a guy was just pulling out now, I paid for the slip 3 months in advanced, sight unseen just to get a slip. Better to be lucky than good.