This would be a pretty big change to the the /warp rp system, and the coding behind something like this would be more complex. I agree that a feature like this could be nice to have, but the overall complexity of building a biome search structure, and then trying to balance that with multiple players using the command to go to a rare biome but not sending them all to the same spot would take quite a while to get right. I'd prefer that our limited programming resources be allocated to projects that impact a wider audience on the server.
I'm a -1 on this. If you really want a specific biome, either spend the time finding it yourself, or pay someone you trust to find it and /tpa you there.