[HerenIstarion]

When I hear 'gnome' I have an association (or would have had if not for BoLT books) of a dwarf - i.e., someone less in hight than a human, and bearded, and probably living in a cave or under earth, guarding hidden treasure, not a higher than human, beautiful and unbearded (unless in a third stage, like Cirdan) elf.

(On the other hand, I would have had mental picture of something bug-sized and fly-winged for a word 'elf', if not for Tolkien, but here I stray)

'Orc' (for a dolphin) was an obscure word (per instance, I learned that once it stood for a whale after I learned it stood for a goblin and got the concept rooted in my mind), whilst 'gnome' more widespread. It would have taken more to change mental association for 'gnome' than it took for 'orc', I reckon, so the drop of term was justified. Besides, in later years Tolkien spelled it 'ork', to further distinguish it from a 'whale-word', since it came not from ir, but from Quenya through Sindarin (Quenya 'Orko' (itself variation of 'Rauko' - Demon, i.e., something to be afraid of) became 'Orch' in Sindarin and 'Orc' in Westron, so it must have been a coincidence)

Besides, I have a strong feeling that Gnome (being Greek word) suited Tolkien's palate (even if it was unconscious) less than perfectly English (Germanic, Gothic etc) words like 'elf' and 'dwarf'. Probably, something along 'wizard' (i.e Deep Elves - Knowledgeable Elves - Wise Elves) might have been devised for Noldor, but that what would we have called 'Istari' than?

And finally, neither one of other two High Elven kindreds is tranlsated (unless we count Chapter 8 of the Hobbit and casual remarks here and there), and are usually given as Vanyar and Teleri, so why make an exception for Noldor?