I can totally see your reasoning. I'd probably feel the same if I'd received the occasional epic/legendary card in my reward booster packs. But spending a dollar or so on one card (when you need at least five to level them up decently) it's just not worth it. Not so with reward cards. Even with the sea monsters I got at the end of last season (enough to bring it up to level 4), I don't want to sell the outstanding one, because I just might get a few more as quest rewards. So yes, I understand the sentiment towards cards that are proven to be useful.