That's one of those things where traditionally the excuse has been variations in the races. Similar to the Andorians, where there's so many variations of antennas and what not over the shows and films (the most drastic prior to this probably being the TNG ones, which were god awful, imho). I'm sure this one will be planted in that same category. On the Tellarites, I feel like there is some kind of neurosis going on where it just could not be left well enough alone over the years. They're space pigs. That's a fun and charming idea. Just let them be space pigs. That was my problem with ENT Tellarites. They look more like a shaved dog, they were made more vague just to not be as much space pigs, and that move takes away their character. Let 'em be pigs. Make it prettier, spruce it up, but don't fix what ain't broke.