A lot of people bag on Sony for being arrogant. I believe that arrogance, in a multi-national corporation, would necessarily mean being blind to market realities and I don't believe this is the case with Sony. They are in these markets for the long haul and that leads me to the following conjectures:

1. Sony realizes that the videogame market isn't zero-sum.

Unlike home theater or personal computing, someone buying an xbox360 or Wii doesn't necessarily mean they won't buy a PS3 as well. Sony bought their own movie studio (MGM/Columbia) to ensure that, no matter what deals other studios cut with other hardware technology platforms, there will always be Blu-Ray exclusives because people are less likely to own two different video playback formats than they are to own two different console gaming platforms.

2. Sony is invested in the PS3 for the long time horizon.

Both the PS1 and PS2 were initially expensive and difficult to code for. Over the lifetimes of those platforms you saw developers gradually learn the tricks and squeeze more performance and innovation out of them than they did initially (compare Wipeout to WipeoutXL on PS1). It's going to be a few years before developers really learn how to make a PS3 sing. Right now they're saying that, even though the PS3 hardware should outrun the xbox360 (e.g. Folding@Home) in the real-world you're not seeing much difference. This will change.

3. Backwards compatibility can be sacrificed.

Gamers are used to running multiple platforms. The initial presence, and recent dropping, of backwards compatibility is entirely related to availability of software. Sony said (and I take them at their word on this because it makes sense) that they now feel there are enough titles for PS3. A year ago, you weren't going to see mass adoption of PS3 because there were few games. To keep from pissing off people who bought them and then couldn't play the latest games, backwards compatibility was a smart move. It wasn't designed to encourage people to pull their PS2s from their rigs, especially since there was (and is) still so much PS2 sales and development happening.