I personally think that them taking so long to make new avvies helps make the current ones they have more valuable and worth getting. If they kept releasing new ones, eventually no one would want to collect the avvies as much because they would be too over-done.
I agree that seeing people whine about avvies being too hard to get in the neoboards got to be pretty annoying for awhile there.
They're also probably working on getting items made out for their new Petpetpet habitat game they're creating. I'm glad they're spending a lot of their time on the wearables right now because there's not much available that's worth buying just yet. Perk up, though! I'm sure they'll start releasing a few avvies here and there soon enough. ^_^