There are a handful of people who're currently doing the heavy-lifting for Bitcoin development. And most open-source projects work like that.
Increasing diversity of Bitcoin implementations is important. But it's going to require a lot of work:
- We'll need to attract experienced C/C++ engineers to Bitcoin development and give them a couple of years to catch up.
- We'll need to cleanly separate consensus-breaking code from non-consensus breaking code and have formal methods to verify implementations against protocol specifications.
- We'll need better understanding of hard forks and voting on protocol changes in the real world. This means better testbeds, more real-world experiments on smaller blockchains, fallback mechanisms etc.
- We'll need a community that respects difference of opinion, studies the subject as a science, and adopts high-quality peer review practices.
Bitcoin is a baby and will eventually mature to support a diverse ecosystem of implementations. But that is not likely to happen for many years.