I only ever really "need" two: regular Elves and Drow. I consider the latter more suitable as NPCs, so I would have been fine even if the PHB had only one Elf, and the Drow were relegated to the MM. OTOH I think it was a good idea to have two in the PHB, considering how divisive the topic "how should an elf be" always is. Having both a magic-focused and a nature-focused version since the start really helped avoiding arguments.
I haven't had time to be a player much in 5e, and so I haven't actually played a 5e elf PC yet. But in 3e I've played High Elf, Wild Elf (Grugach) and Drow PCs. I don't mind if they put out a few more subraces, and I liked the UA previews. The only elven subraces that I typically find off-beat are the aquatic variants, for some reasons.
Until Elves rule the world...never enough elves...or was that Orcs...
Morgoth is never really clear in his communications...maybe he should have a better messenger to deliver his letters than that werewolf/vampire named Sauron.