We're SSR owners and lovers...I think there are two basic reasons why SSR's reputation is what it is:
1. Size: It's BIG. So there are LOTS of points and owners. It has availability long past when other resorts are sold out. I believe this is more because it is so big than because of any negatives. It doesn't have that "exclusivity factor"...
2. Location: It's not connected to a park area or hotel -- one of the reasons SSR appealed when I bought in 2006 was its proximity to Downtown Disney (and the advantages that brings with respect to transportation to other resorts)... BCV and BWV appeal to me because they're walking distance to Epcot & the Studios; and BLT appeals because I can walk to MK. Wilderness Lodge is small and therefore exclusive, but its lack of walkability to any of the parks is to me a big negative. AK has its animals...but I feel almost "imprisoned" there--you can't walk out of the resort at all...so AKV is my absolute least favorite resort, despite the fact that it's gorgeous and the animals are cool and I do like it.
So, I think it's a combination of size (lots of villas means lots points means lots of availability and therefore little exclusivity ... it also means more resales, and the more resales (to a limited number of buyers), the lower the price...
Having said that, there are other reasons: personal taste--SSR is "blander" in terms of its theming. It's condo-style rather than hotel style (outside (tho covered) hallways rather than inside-the-hotel hallways). It's spread-out so you if you don't enjoy walking (strolling the grounds) you won't like one of SSR's key appeals (to me, anyway)...it's also a golf/spa resort--those amenities appeal to lots of folks, of course (I'm not one of them), but it seems there are fewer people who prize Disney and
DVC for the golf and the spas (as compared to the parks and "Disney magic")...
Anyway, bottom line is that IMO SSR is a terrific resort, with lovely amenities, great service, and I think the best transportation at Disney (I've never quite "gotten" the appeal of the monorail...the transfer from the MK line to the Epcot line,w/its steep ramps and significant walk on concrete, is to me much less pleasant than a Disney bus...crowding seems about the same--but I admit the trains do seem to come more frequently than the buses)--
But because it's so much more likely that there will be availability at SSR later in the booking year, it's where people who decide to go at 6, 5, 4, 3 months out frequently wind up. Because it feels like they have no choice, it gives the resort an air of "second class"...
Just my thoughts. I have been a huge SSR fan from the beginning of my DVC experience...and don't foresee that changing...