The main difference between DS/Wii and PSP/PS3/X360 is that third parties need to release a lot of smaller profitable games on Wii/DS to make alot of money because Nintendo dominates above the 2m unit level worldwide. But since you can profit at 100k or 250k, you could release 10 500k level games, and do as well as having only 5m game on PS3 + 360. That was essentially Ubisoft's strategy until the DS software market began shrinking last year. Other strategies that have worked are Sega's hits on Wii/DS (Mario & Sonic), and Sqaure-Enix's hits on DS offsetting generally less profitable projects on other systems. But for most publishers, the goal is to release a ton of modestly profitable DS, and PSP games, have a couple break out hits on Wii, or PS3 + X360, and release surefire blockbusters on PS3 + X360.
That said, we hear all the time about how the Wii costs 2-4 times less to developer for than PS3/X360. So the third party market has to reach 2-4 times the Wii size on the HD systems to kill the Wii for third parties. It won't be happening anytime soon. The ~90-110m / year third party Wii market can sustain 400 profitable games in theory, whereas the ~170m / year third party PS3 + X360 market can sustain 340 profitable games at double the development costs. For the purposes of ease of making profit, the Wii software market for third parties is bigger - thats why the system has so many more games.
People are difficult to govern because they have too much knowledge.
When there are more laws, there are more criminals.
- Lao Tzu