Lucky,
I have noticed this too, and think it's a huge bummer. Last year we won two Skyauctions, and used them together for back to back weeks at Orange Lake over Christmas...one was an RSG auction and we paid about $251 total (bid + fees) and the other was for a 2-bdrm villa where we could choose the resort from a list of available resorts and dates. We paid, maybe $421 (?) total for that one...so about $672 for both weeks, which we thought was a great deal. Haven't seen anything like those deals recently.
I agree with you also about the Fairfield timeshare offers...ugh. And though I don't know why Skyauction has changed in this direction...I agree that it could definitely be due to both the website's increasing popularity and an improvement in the economy, with folks wanting to travel again.
Good luck to you in finding some deals!