That's a fair and valid point. I firmly believe that live reloading of individual apps on your ESP32 during development is a big win for productivity, but clearly so is an established and mature ecosystem.
There are ways and we've seen successful integration of C++ libraries and functionality - but it is not what I would call easy yet.
Toit is evolving rapidly and we find that being fully open source helps our users tweak things where necessary. It's been a fun ride so far and we've got some pretty awesome and sophisticated use cases that involve custom C++ code.