I think they need to (and from some posts I believe it is being looked at) tune the card distribution a bit more. I'm lvl 16 and it's still the same. I think the only "new" card I've seen in the past 5 levels has been Augury, which I can completely understand if they want to make it higher level than other B level cards, but there should be other cards popping up in that range as well. I expect, based on other posts, to see a lot more cards appear as I approach lvl 20, but yeah more really need to be redistributed between 10-20.
As it is, while I find it somewhat entertaining to "level" a group of guys in quest mode, I'm only really doing it because the story mode is unfinished. Long term I'm much more interested in playing groups through the set unique story missions than replaying endless random quest missions where you encounter the same stuff over and over. Which is even less exciting if you're not even encountering much in the way of interesting cards from around level 8 (by that point you have all the good boons that are available early other than 1 or 2) to at least level 16.
Personally I think you should get both gold and XP for time spent rather than having gold be somehow tied to difficulty / ability to complete missions (except as maybe a completion bonus) but that's just me.
Agreed about difficulty tiers. I'm usually someone that likes the challenge of playing on a higher difficulty but that difficulty needs to be balanced and winnable if you know what you're doing to be interesting for me. Right now it needs some major tuning (Night Approaches alone is extremely unbalanced) so I've just been playing on normal. If balancing happens, I'll look at it again.
I am level 25 ill hit 26 in my next quest and I have never NEVER seen augury. I wonder as some have speculated that the card pool is augmented by your party and I wonder if augury is tied to Seoni or something. I have been fearing that things like Augury and Haste got bumped up even farther because of how good they are and not knowing is really starting to be frustrating. I run Kyra, Ezren, and Lini. Right now without Augury and haste the only thing that keeps ezren's deck recycling is detect magic. Also no staff of healing yet, WTF?