[Man-of-the-Wold]

An unspoken undercurrent is that Elrond and the other remnants of the Eldar had done their part over the previous thousands of years and had other concerns. They in effect did not live in the present, even if not actually in the past. Rivendell was a very special and powerful place, which had been pivotal in the Ring's coming into the hands of persons least capable of being corrupted by it or attracting attention, and in assisting and protecting those Ringbearers. It was not their part to push the envelope of destiny and fortune.

I think it is telling that Legolas represented Elves, and though of at least partially Sindarin heritage, he was indeed more representative of those East/Wood-elves (with some Nandor-Sindar influence) who still played a significant role in the more everyday affairs of the N.W. of Middle-Earth in terms of numbers and at least continuing culture.

Elrond may have been reluctant to insert himself or Imladris into what had become a world of mortals. Perhaps, they might have played a small role along with Rangers, who stayed behind, in terms of containing orkish threats out of the Misty Mountain or of aiding Lothlorien or the Beornings.

Also there was the estrangement with even the Edain, and that while Gandalf was still accepted as a "wizard" in the guise of an old man, an immortal high elf would not have mixed well among the Rohirrim or even the Gondorins. Also, the movement of such a personage would have been easily marked by spies of the enemy. Recall Gandalf's regret at revealing his power in the Redhorn Pass, or that after his return he still used his grey rags to conceal his new strength and light. Glorfindel would have stood out -- shown or shined -- wherever he went, and little could have counteracted his nature.

Three final points: (1) An overriding strategy was to occupy the Enemy's gaze, and Elrond's and Glorfindel's staying in the North would have kept some part of Sauron's attention directed that way. He would have still viewed them as a threat and a focus of his Malice, even as Elrond knew their role and powers to be passive and no longer meant to project power in an aggressive sense. Consider Varya's attributes. Their only true contribution to the cause was Sauron's fear of them.

(2) Elrond may not have wanted himself or any of his people to be tested by prolonged exposure to the Ring. They were still at heart proud and powerful High Elves, who probably nurtured some some sense of how they thought things should be. Gandalf and Aragorn had already passed the test, and in fact, possessed simpler, purer types of nobility and strength, and they appreciated the world of Men. The others of the Nine walkers were generally less complicated and unaffected.

(3) More Elves would have meant fewer Hobbits, which of course, could serve as decoys, even sacrificial ones, but also could step in as substitute ringbearers, if necessary. Unexpectedly, they also played the role of non-intimidating emissaries among Ents and Men.