the annoying thing is, some computers dont support java 7 or below,
currently, its only osx 10.10 (yosemite), doesnt support 1.7 or below
luckily for most people, there is 0.78% of servers on any version of osx, even less on osx 10.10
sadly, this means, if i release a plugin, only 9.32% of server owners will be able to use it…
I think it’s an incredibly short-sighted decision to support Java 1.6 when upgrading would only effect a very small percentage of people.
Even though Sponge will be built around 1.6, does that stop us from using 1.8 ourselves when writing plugins for it?
Nope 
also, people who use java 1.6 are missing out on almost every plugin that you can get
and, if sponge is moved to 1.7, the worst that can happen is some people will need to update to 7, its not the end of the world
It doesn’t stop you but please don’t. Write for Java 7 like everyone else until 8 becomes more supported. You’d wind up with /a lot/ of users who don’t use your plugin because they don’t want to update Java when they’re already running an actively-supported release of Java.