Write your own and keep it simple. It's not that hard.

The ones you can buy however are a nightmare for sure, so are most of the copy-pasted-glued-together ones.

Admittedly, it was a few years since I looked at the inside of wp, but it was horrible, with php api calls inside the template code, bad/missing/misleading documentation and non-existing database structure.

I have, and I somewhat disagree. I agree that it can feel dirty to your programmer sensibilities when you start from the base template one and go "building from the ground up", but if you set expectations accurately with the client (and yourself) wrt the amount of flexibility a theme gives and what type of work you're going to be doing, you can get some pretty high quality themes (where "quality" here refers to the template's ability to fulfill the goal of offering a feature-rich GUI to non-techies). Some themes are so elaborate that you can change virtually every aspect of the template down to the most granular levels directly from the admin interface.

And where wordpress really shines is in the ecosystem. Subscription list popups, SEO, social media integration etc are just a few things that clients commonly want that take far less time to integrate into wordpress than building from scratch (because it's fairly common that authors of less popular developer-centric CMS'es didn't think to implement those things).

Come on, nightmare? It's kinda annoying, fussy and handle-turning, but taking a page that has been designed and fitting that into the template tags is really not all that bad for a days work.

I had to clone a website, then make a few tiny adjustments (like change the site name), and it took me several days.

> Have you ever tried to modify ikea furniture? It's a nightmare. And we are professional carpenters. Imagine the pain this must be for mere hobbyists.

Bad analogy. My brother (who is a non-carpenter web designer) shortened an IKEA bed recently. Apparently it wasn't a big deal.

> And we are proffessional developers

In my experience, WordPress is not built for developers or designers. It's built to be simple and extensible from the end-user's point of view. Most end-users don't expect absolute perfection and accept that it will do 90% of what they want. As long as it keeps doing that, no one will care what a "mess" the insides of it are.

> no one will care what a "mess" the insides of it are.

...except the poor bastard who will have to build the website and maintain it.