I have some friends that are Mormon and have met others through them. While they're just as conservative in a lot of things as the JWs, they tend to try to fit in with the world around them. They may shun some of the more "perverted" things, but they want to be accpeted, not persecuted or laughed at. They may promote "cleanliness" but they don't have hard and fast rules as the Society does...like no R-rated movies, no heavy metal or rap. Mormons are encouraged to discern what is pure and chaste but aren't given strict arbitrary rules.
As a group they encourage higher education (they even have their own college, BYU). They join and serve in the military. They hold political offices. They're in the entertainment industry (if you can call Mormon pop music like Donny and Marie entertainment). (another sidebar: I've noticed that most Mormon celebrities do little to bring embarrassement to the church while JW celebrities are usually embarrasing and some are downright nuts)
I also know that they have youth programs in their churches and communities. That's one thing that JWs could learn from them. The Mormons probably have a higher retention rate of followers from childhood to adulthood than JWs because they make such an effort to provide safe a safe environment for their youth. (but then again, it may be a blessing in disguise that JWs show no regard for the youth, thus driving them away).
I can see the "cultural Mormon" thing having known some. They're probably a lot like Catholics. I mean, how many Catholics really hold to all that their supposed to? Similar to the Mormons...the more mainstream they become, the more "cultrual" a lot of their members can be.
It's been noted on the board that it seems that the Society, or more specifically, the GB is dropping the hammer more on the dubbies lately. The more iron-fisted they are the less chance of having a "cultural" JW. You're either active or inactive. And I think that's what they want...to make it hard so that those who rebel just leave. If they're out of the way, they can't distract the hard-core followers.
Another reason you don't see too many "cultural" JWs, there ain't much to gain from being a JW even without being active in the service or going to all the meetings. If you're irregular, you're usually marked pretty quick, thus slowly dissolving any camarderie that was there before. So why bother hanging around?