Just got a land title from the department, as well as some kind of Residence book. They told me its mainly for Thias to do the registration at the local office, but also said foreigners don't need to do it, but can. Is there any need to do it, but also any benefits of doing it?

It's not necessary, however if you want to learn more about the benefits, read the pinned thread called Yellow Tabien Baan.