Earlier quoted context omitted.
> should be a solved problem by now, and not require every developer to ask themselves these questions again and again This applies to so very much of web developement. We have spent so much collective time building web apps, and some have also put a lot of time into building libraries and frameworks, that with all the brainpower and effort, things should be easier now than they are. I believe this is because we've h…
One of the benefits of Wordpress is that it runs on PHP. It's very easy to find a cheap web host and just copy the files over. Many web hosts even have a simple button that sets it up for you. A viable alternative would need to be just as simple, and currently that implies it should probably be implemented in PHP, which will exclude developers who want experience with "blog-friendly" languages.
A good foundation can be in any language, such as PHP. But it needs to have a modern, better architecture with a more consistent base library/API for the plugin writers to take advantage of. WP is like 1.0 of this. We've learned so much in the last 10-15 years; it would be nice to have a completely rethought foundation.
But for the plugins, I think there should be a standard interface layer (based on probably http, tcp, pipes, files, even memory stores for communication). Then plugins could be written in any language, hosted locally or remotely, and sandboxed.