For regular users, and those who aren't submitting changes, for ports, Portsnap is better. It takes 5 minutes to extract the ports tree, and takes little time to update. Git takes over an hour to update the ports repository. This is after git was claimed to have been improved.
It's a relief that Portsnap will at least be available in ports. It not being in base, is going to affect how many people use the more practical program. The difficulty to learn basic tasks and time it takes to update ports using git, is going to discourage a lot of potential new users from FreeBSD. People want to use the system, and learn its essentials, not some program which is a task to learn on its own.
Try using git, and it's not easy. The definitions of it aren't self explanatory. You can stumble over the commands you want to use, because the description doesn't match what you're looking for.
What is it that someone has against portsnap?
https://git-scm.com/book/en/v2 is the freely available through Creative Commons book on Git. Even if all you need is the first 3 chapters for most purposes, it's not easy. Simply downloading ports tree for that task, isn't so bad. The rest of the tasks, you can't even find what you want even when looking at the desired commands.
It may be because they insist on when uploading bug fixes to update ports. The less complexity and the less unnecessary dependencies there are, would omit the need for an exactly completely updated ports tree for the programs to compile correctly each time.
If they can't make a Git type of program run with the ease of Portsnap in speed and simplicity for those who simply want the Ports tree, that's not a good decision to leave Portsnap out of base.