I can appreciate your disappointment. These games, videos, lessons and quizzes are supposed to be educational, entertaining and fun. The rewards, well they are not like they used to be years back for sure. Points don't buy what they used to. That said, neither do $5 cards. It does seem that $15 Instant Wins are becoming more common.
But ask yourself, if the $5 cards you want disappear in minutes (seconds), then announcing the release time for $10 cards could be even more challenging to get one.
I think AARP is spreading "For Points" cards released through out the month at various times to also be available to West Coast participants.
Reading several threads on this forum, I see a lot of frustrated people. I consider myself fortunate to buy a few cards a month, not always my choice of vendor, but it gets me to try new things, like Chipotle, shop at AutoZone, send flowers, candy or popcorn. Once in a while, I get an Instant Win, and maybe once a year or so I get a card in a drawing. A little bit of something is better than a whole lot of nothing. Yes, I am retired, so in-between playing sudoku and solitaire, I check offers.