I agree with the OP, spending avios is getting harder and harder. The only way I managed to get my last two redemptions through was using GGL jokers, and even those required a little flexibility in terms of dates, routes and cabin.

Not ideal, but at the same time the OP describes pretty accurately how easy it is to get avios. Increased number of avios in circulation meeting the same number of available seats, and sure enough the value of avios approaches that of the Zimbabwean Dollar.