It's not surprising that changing a language would be difficult. It does, after all, include a software component, and pretty much all large software projects suffer the same. It can be easy to change minor technical details, but a deep, far-reaching design decision is very often fixed in place. Even with a good test-suite, that kind of change is rarely undertaken. At least in my experience.

I suspect we've all worked on software that you would desperately love to change something fundamental in the design but no matter how painful leaving it alone is, it is preferable to live with the pain than to tear it all down.

I've known a few writers for example that say they wish they could change their characters, but it's too late. I wonder if that's analogous.