There's a long history of distributing source code already partially processed, and for decades, this has been what people expected when they download a source tarball. Newer generations were introduced to open source through github and are less familiar with this, but they also are rarely interested in source tarballs — they're interested in either the source code to contribute to (in which case they'll git clone) or in a binary distribution.
Really the main purpose of source distributions is for packagers. Especially when you're creating pkgbuild scripts like for archlinux's AUR or gentoo or slackbuilds or macports or BSD, all the tools needed to build the source code become build-time dependencies for your package, which is annoying for people installing it.
Not having to add autotools to a BuildRequires is nice, but hardly the end of the world as a package maintainer. I agree though, the contents of the repository at a git tag is not necessarily a source DISTRIBUTION - which is what most people who are compiling your software would want - especially when many of them probably don't know the autotools incantations required to generate the configure script.
We probably need to do away with partially processed source and distribute just the git repo (or a tarball without .git but with info about which git rev it is) and binary packages for end-users.
Really the main purpose of source distributions is for packagers. Especially when you're creating pkgbuild scripts like for archlinux's AUR or gentoo or slackbuilds or macports or BSD, all the tools needed to build the source code become build-time dependencies for your package, which is annoying for people installing it.