I dont like dragons only being able to move one square. I say balance them out with other bad a**ness. With technology that allows you to build balistas that have an advantage against dragons, or weakness for the dragon to the opposite element type like fire-water etc. or special rare material that does special damage to dragons dragon glass. etc. I would do this while making a dragon hatch costly, like the dragon eggs are all dormant petrified and you have to do blood magic to revive them (like in Ice and Fire) and costs you your firstborn son or favorite merchant.
Its a dragon, get over it.