So you have two fundamental problems with trying to define ELF in D&D: subspecies and setting.
D&D has several species of elf: High, Wood, Drow, Sea, Eladrin, Shadar-kai, Astral, Averial, and Wild just to name the most common/recent ones. The overlap shared between ALL these subraces is rather small.
THEN you add on the fact D&D has several settings, each producing different cultures of one or more of the above-mentioned subspecies. Grey elves, valley elves, sun elves, moon elves, Aerenal elves, Tarinadal elves, qualinesti, kagonesti, silvanesti, dusk elves, shadow elves, Vulkoor, Sulatar, Umbragen, Udadrow, Aevendrow, Lorendrow, Athasian elves, and probably even more obscure variants I'm missing elsewhere.
And all of these elves are supposed to be represented by one set of stats in the PHB? I don't think so.
D&D elves HAVE to be bland because look at what they are trying to fit under one roof. If you wanted ELF to have some meaning beyond pointy ears, you set fire to about half those subraces all most of those alternative D&D worlds. Then you might be able to create a consistent vision of elf in D&D.
But nobody is willing to sacrifice 90% of the current D&D settings and their favorite variant of elf to achieve that. So elf will remain broad and vague because of all it has to mean.