I think they show the latest commit to match Git's model where each commit has its own file tree. If you are looking at an old version of the code, the latest commit for that version uniquely identifies that version. I suppose they show the latest commit as part of a way to prevent people from getting confused which version of the code they are looking at, when they look at past versions of the files. But I think in the case of the project main page, the latest commit is too rarely used to justify being shown by default.
I think GitHub should only show the full latest commit when browsing past versions of code. Otherwise, it should show just the text "latest commit for the master branch", or that commit's SHA ID, or the date of the last update. If allowing people to measure project "freshness" is important enough, maybe they should instead show the 52-week graph of recent activity, like on users' project lists.
I think GitHub should only show the full latest commit when browsing past versions of code. Otherwise, it should show just the text "latest commit for the master branch", or that commit's SHA ID, or the date of the last update. If allowing people to measure project "freshness" is important enough, maybe they should instead show the 52-week graph of recent activity, like on users' project lists.