Disclaimer: I was formerly Lex's forum hunting dog so my views may be biased and prejudiced.
I don't think staying on one MC version is good in the long term. Users are stupid - believe it or not, most don't even know how to change the version in the vanilla launcher!
While I may be repeating Lex's rhetoric here that we should be on the latest MC version at all times, I do it for different purposes. I've seen the kind of people that play Minecraft. People that go "Y NO HORSES HORSES ARE MINECRAFT" when I show them a version of MC without horses.
Are you willing to backport any new toys Mojang adds (and the corresponding frameworks around them)? It'll just result in more hacks all around, making work for people like NOVA leagues harder. And there's also the question of whether a backport violates Mojang IP. They have MS and the MS legion of lawyers behind them now.
Remember, whether a mod (or an API, for that matter) can make it or break it depends on the players. So you need to take into consideration the players' welfare, unless you want to be a small obscure mod catering to 10-20 people at the most.
Ultimately, I think the best way forward is to keep up with Mojang, but with enough discussion and dialogue surrounding the API so that we cal all survive the update together.