And? Where's the flaw in logic here?
Doing direct face damage ISN'T priest's identity, and as such a card that does only that does not belong in priest's classic or basic set, which are almost entirely focused on what should and shouldn't be each classes individual strengths and weaknesses (Of course there are hits and misses, and hopefully blizz irons out the misses).
This is an expansion set themed around dragons, akin to how Whispers of the Old Gods was themed around, you guessed it, the Old Gods and a what-if scenario if they all emerged again with a lot of cards being corrupted versions of older cards. So of course the dragon-themed expansion set is going to have DRAGONS in it. For every class. This has been a very common tactic for every single TCG ever.
An example and pretty direct comparison is MtG's "Khans of Tarkir" block of sets, which were ALSO all themed around dragons, and suddenly there were mono-colored dragons in all 5 colors, despite the fact that dragons are primarily red since the game's inception, with only notable legendary dragons (who were important in the lore) breaking out of that piece of the color identity.
4
understand that this is giant powercreep compared to most other 9 drops
understand that control warrior likes 9 drops
this will see play
10
duh its not intended to ruin adventures
2
why is it a legendary, IT NEEDS LORE TO BE ONE!!!!!