In the quest for simplicity, R3-Alpha had an aesthetic that tried to be very minimalist in the source tree.
The top level had only this:
make/ src/ .gitattributes .gitignore LICENSE NOTICE README
The %make/ directory contained:
makefile makefile.vc vcbuild.bat
The %src/ directory contained:
boot/ 20 files core/ 95 files include/ 31 files mezz/ 31 files os/ 7 files, with 2 directories of about 10 files each tools/ 10 files
The files themselves vary in size, but this just gives a perspective of about how many files there are.
Ren-C and Red use MANY more files and directories, BUT...
Largely I think this is okay, moreover can be beneficial to understanding the code.
While we should be skeptical of large amounts of complexity, I don't think there should be a kneejerk reaction to a lot of files.
Filesystems were invented for a reason: organization. If arranging things in separate files makes the organization clear, it is good.
Yet there should be some justification for why a directory exists. For instance: I think every directory should have a README.md in it, which explains why those files are grouped together.