The only way to cater to third parties is to weaken your first party, or to weaken the competition of other third parties. The whole key to 3rd party sales is lots of attention on your title, and a lack of competition from other titles.
I think the topic title is pretty much the truth when it comes to dealing with third parties. Nintendo gets knocked for their lack of 3rd party support, but Nintendo themselves really went out of their way post-n64 era to get more third parties and to make their platform more third party friendly and cheaper to develop for. Even so, with the DS at the top right now it's Nintendo and Square doing all the work. That's how it is and how it will be, and if Square increases their output(which it looks like they are doing) on the system then that is how it will stay. Nobody can compete against monthly releases from publisher's of Squareenix and Nintendo's size and stature every month, no matter what system you are developing for. It's not that the audience wouldn't give your game a shot, or that the company gave you a shotty setup, it's just that if you could choose between a Lexus, a Mercedes and an unknown and they all cost the same amount... people will buy the Lexus or Mercedes. That is the issue when you go up against strong first party support.
Sony consoles succeeded because their first party was not as strong as Nintendo's and this opened up things for 3rd parties due to lack of competition. Now look at what Sony's focus has been with the PS3, their own first party software, and what do you see? A third party exodus. Where are some of the games going? To the 360. And why? Because outside of Halo, MS' first party is pathetic. There is no competition, every month is open space for whoever can put something half-decent out. Lego Star Wars 2 is a nice game, but it wouldn't sell against a Nintendo or Squaresoft or Gran Turismo. On the 360 though, it can grab the spotlight for a little while.
So, you can't really cater to third parties without fucking over your own in-house development. This is why I roll my eyes whenever media twats talk about "third party support", because good third party sales means you normally have equally bad first party sales. Then the media compounds their ignorance by promoting the hype/pr fest that typically highlights one game in contrast to the variety of software that is available. The media really helps make it a self fullfilling prophecy.
