The real problem is that there are no good alternatives, that Delve (and soon RME too) are too far ahead of crafted weapons and other more common weapons.
Bayld weapons should have been way stronger than they are (latent DMG should be the default DMG). Skirmish weapons should be slightly increased, and the best augments on skirmish weapons should make the weapons slightly better than a vanilla delve weapon. There should also be a lot of crafted gear available. There should have been NQ craftable weapons that were as strong as unaugmented skirmish weapons right from the beginning of SoA, and also recipies with more expensive items for weapons that were on par with unaugmented delve weapons, and of course HQ versions of all these weapons.
Although a bit too late now, I think delve should have been added a bit later, and not in the way it is currently done. I think it would have been healthier for the game if gaining access to each delve would generate AH sellable items that could be used to enter skirmishes as a by-product. That way, the more often people did delve, the cheaper and easier it would be for the lower tier players to gain access to skirmish.