I know that people are excited for the Dragon riding feature in the new expansion. Also even before Dragonflight, WoW has had Dragon mounts. But it's awfully inconsistent with the lore, isn't it? Like bordering on awkward levels.
We know that Dragons are sentient, intelligent creatures, intensely so in fact. Even if you leave aside their preminent, "august" position among the beings of Azeroth, would any self respecting sentient race of beings agree to serve as beasts of burden for other races?
Dragons have willingly carried mortals on their back in past occassions, true, but these were special occassions, far from being a normalized practice, with the rider dictating terms.
Add in to that the absolute charlie foxtrot of horror that was the experience of the Red Dragonflight while they under enslavement by the Dragonmaw clan, who used them as beasts of burden and war. What makes one think that Alexstrasza would react in any way that was friendly, to this proposition? Or even the other ex-Aspects for that matter.