I agree and don't think it's limited to programming. Considering business, it's difficult for a large established organization to make drastic changes.

It's much easier for a new entrant (startups) to innovate because they don't have the same baggage.

I think this affects version control systems specifically because the nature of the beast is to create a format to track changes over a long period of time. Changing that format is a huge pain in the ass and rarely worth it.

In VCSes more than in regular software, you really have to get the design right very early in the process.

When an improvement comes from a new mental model of the data/problem, it's at least as much work to fix X as to write Y from scratch. Generally much more, as you must figure out how/whether to interface old features to the new model.

Similarly, in the case of changing mental models, most users and even developers of X won't be ready for Y when you write it. Trying to force the change onto those people will harm X and handicap acceptance of Y by confusing the Case For Y with the Case Against Killing X.

So it's hardly surprising.