I think that WordPress rising in market share would also drive the being dreaded number. In the 90's and 2000's Perl was all the rage, but if you asked anyone now they'd be loathe to deal with Perl. So to some degree, I think it comes with the territory of being more popular.

How can we make the software more developer-friendly without compromising user friendliness?

Here is the root of the issue presented. I have seen several core/lead devs say that WordPress isn't built for developers, its built for users. This has effected many decisions such as not allowing frameworks in the plugin repository, pulling options out of wp-admin, and heavy emphasis on improving the customizer, the way certain functions in WordPress behave, etc, etc, etc.

Decisions must be made with the developer in mind as well. As Otto frequently says, it's just code. We can write code that is easy for developers to consume and users to, well, use.

That being said, I do think more preference should be given to the end user. Because in the end, they are the people dealing with it. There's a reason they are called the end user. However, it shouldn't be that hard to strike a good balance.