I think most people on CAG, SD, or other "deal" sites are trained to wait until an indie game gets either cheaper or bets bundled.
For Papa and Yo, I do like that the sale includes a version that includes the soundtrack.
As far as incentives, amazon is matching. If you like amazon and want to reward them with the sale, then great. Their customer service and Tony are much easier to deal with / communicate with than Steam. Of course, if amazon gave extra incentives, then nobody would complain.
I think though that gamers are living in a time of plenty compared when games were not being published/released as readily. We have also become accustomed to great sales i.e. Winter or Summer sales, Mayhem, just to name a few. Gamers want deals all year round and have become trained to watch for the next deal around the corner. We speculate all the time about the next indie bundle or how much a game will go down in price for Winter Sale for instance.
For me, just like buying technology i.e. a newer computer, it is about coming to terms with when you buy in. There are plenty of discussions about backlogs. For me, I ask myself, am I comfortable with buying in at this price for this game at this time. I know that eventually if I wait, games will become cheaper. Some are worth waiting a little bit. For instance, I could have waited (probably until next Spring) for an ultimate version of Borderlands 2, but I decided to buy in when I got the game, psycho and mechromancer packs, and the Season pass for about $26. I bought BL2 base first and enjoyed it enough, that I bought the DLC and do not regret buying it.