Yeah, but KD, that's an easy fix.
Explicitly set your Dragons to be immune to Pull, Push, and Slide powers, or to have something akin to the Dwarvish resistance (reduce by 1 square), maybe "reduce by 3 squares" for a Dragon.
Yeah, I can see my players liking that (not).
I did just recently run an encounter out of Revenge of the Giants with the giants that shifted 2 squares when attacking, attacking with threatening reach, and also having "reduce forced movement by 4 squares" IIRC.
The players were a little annoyed that their normal tactics did not work. Come and Get It, nope. Charging a giant, nope. It would OA and shift off to the side. The giants kept attacking and shifting and retreating, all in the same round. Drove the melee type players nuts. Whomever designed that encounter deserved a "that'a boy". The players were a bit frustrated during the encounter, but were really stoked from succeeding afterwards. They felt like they had really accomplished something instead of just swing and hit, swing and hit, use the same powers over and over. They had to really work at it and come up with some new tactics.