On the RNG side I might slightly agree there - I got my last epic only slightly before my last legendary (at level 740, btw), and aside from stuff that isn’t in chests yet, epics are the only troops in my collection that are actually still Epic or below. Coupled with how useless a lot of the Epic troops are, even compared to rares and ultra rares, and especially if you don’t get them until later, they do seem a bit on the rare side.
On the glory cost side, however, Epic packs are the by far the best value. Even if you won’t use the troop at all, just get as many as you can for the traitstones, with the added bonus they then become easy to ascend and at least this part of your collection will be complete going forward. Conversely, buy light on the Ultra-Rares and Commons (unless you really want the stones) because price per stone is much higher and they are much easier to ascend in the long run. I don’t see an issue here.