Also, adding evil mode won't address half of my requirements for a baseline Emacs experience. There are performance optimizations in Doom that I wouldn't otherwise have known to put in my own configuration. I'm grateful there are people who are taking care of such details for users like me.
Normally, I avoid configuration frameworks. I don't use them in tmux, vim, or zsh. But Doom was the first configuration framework that I enjoyed using.
[1]: https://github.com/doomemacs/doomemacs/blob/master/early-ini...
Also, there are loads of people who need the things you found questionable or unnecessary. Including myself. I use modules for purposes other than adding support for new languages. But for language support, I sometimes need much more than just the first language server and syntax files that came up in a search result. The performance optimization you found questionable is an absolute must, too. Running "doom sync" to apply changes to configuration is a non-issue if that means faster startup.
Doom Emacs' config loads faster than my hand-rolled one did.
So in that sense, with Doom I get a smaller config to maintain, for something that loads faster, while still having a rich/coherent set of features for the stuff I do bump into.
Having browsed the Doom config sources the other day, they put a lot of effort to minimize startup time; there are various trick there that tune Emacs itself to start faster, and can be copied over to one's own vanilla config :).
So the advantage of having someone else optimise a config is lost because most effort is spent supporting tons of optional packages. Meanwhile my hand written config is the definition of opinionated.