Well, as you say, the beautiful thing about open source is that people don't have to wait for an `extension manager` or whatnot, that would let them code stuff within the boundaries we've carefully chosen... instead they can just fork it, add their favorite feature, then submit a pull request to the main project and hopefully it makes it into the 'blessed' version eventually!
Within a well-maintained project, a feeling of staleness should never happen. But also, we're just a few humans and it's all very early still, so... patience, patience!