Cause riding a full sized ender dragon seems like too much. Basically if an endermite infects a dragon egg, itll hatch and become an Ender Wyvern which has only 2 legs and is smaller. It can be tamed with Purpur and you can put dragon armor on it. Also you can have it carry 2 chests or 2 furnaces or a chest and a furnace. You can also "feed" it blocks. Different dyes will tinge some of its scales that colour. Feeding it a flam charge gives it fire breathing abilities, ice gives it ice breathing which slows things down, different potions give different breath effects, and maybe feeding it a Nether Star also gives it an effect. Also to solve the 1 dragon egg problem, respawned Ender Dragons will have a 25% chance to lay an egg when nesting (Sitting at the nest and spraying ender acid)