I agree with Helios' line of thinking (this is one of very few times his thinking/gameplay has been correct, usually it is extremely incorrect and he should feel bad about that).
In my opinion, there are good cards, and there are rift cards.
Paladin of the Flame Dawn is a good card. You would use this card in pretty much any variation of FD you'd build for constructed.
Knight of the Flame Dawn (Vanilla 7/7) is a rift card. You would likely not use this card in constructed if you had access to better cards, but it is still acceptable to pick in rift depending on your picks. It has decent stats and provides some usage, but is not optimal.
So, in short, good cards are cards that are optimal or close to optimal that you'd pick for a competitive constructed deck, and rift cards are suboptimal but still impactful cards.
As is argued by the OP, Warcry is not an optimal card. The advantage it provides for its cost is in almost all cases not worthy of a competitive constructed deck. However, it is suboptimal and still impactful, so it is definitely worth grabbing in many cases in rift.
I just finished a 47 win rift run and many of those games I won because of Warcry combined with Pyr and Sufferer tokens.
Ultimately, it depends on what LM's intention is. Is their goal to make all cards as close to optimal as possible and all playable in constructed? Or is their intention to make some cards intentional suboptimal so their only use is in rift.
Who knows. I think Warcry is fine as it is now, as a suboptimal but usable draft pick.