I think my main objection at the time was that I didn't (and still don't) really trust Poettering, given his history. I still don't like how opaque systemd is - a lot of functionality feels gated behind extra steps that used to be unnecessary.
But I will grant that the benefits have outweighed the downsides. The distro standardization alone has been a benefit for developers and users alike.
I still think we could have standardized on a better solution, but I don't know what that better solution would have looked like.