What I think it entails--certainly it does so for me--is the desire for a single system that is robust and capable enough of handling pretty much any game that they've ever like to play, with a few minor house-rules or modular variations to accomodate the differing vicissitudes of each game. In other words, I think it turns out that most gamers don't just want new bathwater all the time. I think the number of gamers who are "turned on" by new systems for their own sake is a relatively minor number of gamers, and most gamers aren't interested in new systems. They want to use the same system to play all their games.
Frankly, most gamers don't even appear to have a demand for even much variety in setting and game, much less system. Most gamers are content to just play one game of D&D after another, in my opinion. But of those who like variety, they want variety (mostly) in something other than the system. So they want to find the system that is flexible and robust enough to provide that experience, as well as at least sufficiently--if not necessarily perfectly--adaptable to their specific taste preferences in terms of how system should work as well.