Ehh, a multitude of things but mainly Western-biased influenced article (the interview in which this article stems from is an XBox-centric podcast) taking a translation out-of-context. No one purposely makes something hard to develop for just for the sake of it being hard to develop for. It was harder to develop for simply because hardware and the higher potential it had. If money wasn't an issue (which it always is) the devs wouldn't have much issue with the console. The fact that you sometimes needed more time to invest into developing a game on that hardware to reach the higher potential means more dollars spent developing, which cuts into the bottom line; businesses hate that and developers are a business as much as anybody else, even though they are into art and entertainment.
When this article came out, 4 years ago, it was old news already and the discussion had been beaten to death. Not trying to sound like a tin foil hat theorist, but an old issue being brought up again in an Xbox forum while taking a small snippet of a translation and using the context to fit you view? Just saying, it doesn't seem unbiased or even remotely so.
One line in particular though did stand out:
"That's precisely why I haven't seen much difference in the games offered on both consoles. Sure, some look better on the PS3, but the difference is minor, and that's the only improvement I can see. I don't think developers are taking the Sony bait and working harder at harnessing the power of Sony's console. The incremental benefit of doing so, at least if we judge by what we've seen so far, simply isn't high enough for developers to follow Sony's plan."
Before in the article it states that it was Sony's plan to make it harder for the benefit of being harder, now it just seems to be highlighting the potential power of the system. And even with this line the writer is false because many developers did try to and use the console successfully in fully utilizing it's potential, even before this article came out. Another reason as I see that podcast, and this article stemming from it, as a PR-move for Xbox enthusiasts.
From my understanding, the PS2 was a pain because the instructions to work with it were not translated (they were all in Japanese) and you couldn't check for bugs until the end of the process.
Still, many amazing games that were well worth the time invested. The PS2 still pretty much is the benchmark for success in the console business financially, game-wise, and experience.