generally, version numbers will be increased if there are significant changes. It's often simply forgotten by the executing person...
And "a lot" of current changes to Miranda NG are API changes and other code style changes... Normally you wouldn't see a new "release" if it were a Miranda IM plugin as those changes are mostly internal and don't really change the output.
Ok for API changes you would normally see a new build.. or at least if it's an incompatible change as it is for NG (IM rarely had them)
So when you see a whole bunch of updates, they are mostly caused by an API header change... For example when I change or add a comment to "m_core.h", all plugins will rebuild and thus trigger an update, even though nothing changed. So the version number shouldn't increase
Besides the above, Miranda NG does have some managing issues as well... For my own projects, I'm using an automated version incremental system... every build I compile increases the version/revision (or in case of my Git / SVN hosted projects, every commit does, not "tries")
But since all plugins are hosted in one big fat repository here, such systems don't really work that good... well we could create one, one that only counts commits for a given path / plugin, but that might require us to switch to Git or a Linux based build server^^
So let's just hope we won't forget (or forget less) to increase our version numbers edit:
hmm.. now that I think of it, a "comment" change might cause a rebuild, but shouldn't cause the resulting executable to change... unless the compiler got crazy and goes a different way to do the same thing xD So those updated builds might be limited to API changes that change the way a function is called for example. Which again doesn't really change what the program does, so still no real need to increment the version.