How feasible is it for the average Spacemacs user to patch existing elisp packages to work well with Spacemacs? Vim and Holy vs Evil modes are foreign to me. I'm a plain old Emacs user and would hate to choose between the my preferred mode of interaction and access to packages. Spacemacs seems popular enough that a lot of use cases are well covered; maybe it's not an issue.
Looking at Spacemacs from the outside I've got to say users who don't recognize this are missing out on what makes Emacs great. Every interaction you have with Emacs, down to the individual characters you type, is made possible by readily available and fairly well-documented elisp code. You can use edebug to rapidly isolate problems and ielm elisp REPL to tinker. I highly recommend every Emacs/Spacemacs/*macs user read at least the elisp programming manual to get a better sense of what's possible.
Brief anecdote: A couple days ago I ran into a minor interaction annoyance in
alchemist-mode. When I typed
C-c a h r to open the reference card it opened scrolled to the bottom. The content didn't all fit in the window, so it took a moment to notice I was missing some above. A quick
M-< is all I had to type to scroll to the top (even faster for me than
C-home), but I didn't want to do that every time. Using only Emacs' internal documentation and an elisp buffer I quickly worked out how to get the refcard buffer to scroll to the top after it opened. Better still, I added the elisp to my
init.el file and got the benefits right away without waiting for an improvement to get merged and published in a new release. I also made a more intuitive keyboard shortcut for it:
C-c a ? (alchemist's default key command prefix is
C-c a). These simple changes have already paid big returns for my Elixir development workflow. At a glance I can learn more keyboard shortcuts that interface with mix, iex, tests, Elixir docs, project file search, etc.