Unicode's original self-declared mission was to encode all characters needed for written communication in the world.

Wikipedia once had a similar issue, where people used it to add all kinds of trivia and original research. There was a fight between the so called inclusionists and deletionists. The latter won and we now have strict guidelines that ensure everything in Wikipedia has to have strong relevant external validation.

In my opinion, the Unicode Consortium would have been well advised to follow Wikipedia's example. If they really only had added characters with significant organic usage we'd seen only a much smaller number of emojis added and in my opinion to nobody's disadvantage.

But this is easy for me to say. I'm curious how emojis help with your accessibility needs. Has it to do with the fact that they take up little screen space or is it something else?