That's like asking which bean in the chilli made you fart. How often has there been a triple-A title this generation, outside of a Nintendo platform, that had some color, and that placed the value of the gameplay experience above that of graphics, realism, story, mood, or what have you? Little Big Planet, Child of Eden... and that's pretty much it. It's not any one game that's the problem. Most of them are relatively OK. It's the lack of anything else that's not like them that's a problem. Which one game represents the lack of something? That's not a rational question.
No, it's asking because games are largely subjective. I wouldn't classify Little Big Planet in that for gameplay reasons. An attempt at community generated content maybe, but not for the platforming. Child of Eden isn't really AAA - if you count that, then stuff like Portal, Torchlight, Super Meat Boy, Bastion, etc would count, to me.
I'd also say it's unfair to disqualify games just because they also succeed in those other areas. Demon's Souls is very moody, but it's also highly about play mechanics. Same with Starcraft II, or even arguably most online shooters. Plenty of AAA games have perfectly solid mechanics underneath.
I ask because most of the formative PSX games I can think of were, again, more of a return to actual gameplay compared to the FMV-laden "experiments" of early disc-based games.
It might seem that way to you because Sony does not visibly make a lot of games. However, every console manufacturer has some influence--whether by policy, by example, or in most cases a combination of both. Here we have a lineage of platforms that from the beginning has proclaimed more than any other "we want games to be more like cinema" and has geared their hardware to that end, and has encouraged developers to trend toward realism and cinematography... a company that has through its marketing cultivated an audience that is specifically looking for this experience... Afterwards we have these trends going strong in Sony's library and almost not at all in Nintendo's (nor Sega's when they were viable)... and Sony somehow has nothing to do with it?
Not nothing, just not at the root of it.
Sony looked at the trends in gaming and built a machine around supporting them because they wanted to attract developers, and that's what they did. Of that generation, the PSX was by far the easiest machine to code for, especially for increasingly more common 3D. It used a cheap and flexible disc format.
Meanwhile Sega was coming off of trying to push the Genesis/32X/CD, and presented developers with the convoluted hardware of the Saturn to try and figure out. It wasn't as though Sega had all the major names anyway.
Or you had the N64, which presented yet another system that was hard to work with, and combined it with costly, limiting cartridges.
The long and short is that Sony did their homework and presented developers with a machine that was a lot more inviting to make almost any kind of console game for. Not entirely surprising that so many did. For Japan, some would say that the gain of Square (particularly) was what secured things for Sony.
Nintendo has never been able to get the developer support back that it had with the SNES. First due to perception with the GC, then due to not having similar enough hardware with the Wii. Sega had problems with developer support too. MS as well to a point (without a wad of cash in hand at least).
Ironically, the PS2 and PS3 have been the exact opposite of that initial hardware "advantage".
I think how Sony handled things back then certainly played a part. I just don't think that the current landscape of game genres was some master plan of theirs. They just managed to attract developers, then keep them.
Do not confuse blood and gore with maturity. That said, Nintendo's strict policy of censorship ended during the SNES era. Look back earlier too. Death Race? Morbid games have been around nearly from the beginning, so the suggestion that games need to grow up is a false one even in that narrow, immature reading of it--although I've never seen any other fanbase but Sony's get so hung up over content ratings.
No, the far worse suggestion is that games needed to grow up by becoming "more serious"--that the primary focus should be on realism, or on story, or on cinematic composition. There's not anything inherently wrong with attempting these things, but it's a misguided idea to suggest that this is what games are about, or that it necessarily should be.
I don't confuse gore with maturity. I simply point that out as part of the overall shift in public perception, and what was finding a market. Console games weren't necessarily kids stuff - not new, as you mentioned, but with graphical fidelity going up it was simply more apparent.
To me, it's less a "need" to grow up and more that as hardware specs and potential sales go up, so can ambition in design. It's perfectly understandable that the focus would shift on what the new platform can do that the old one couldn't, which in this case would mean games that were a shade more complex than before.
Or, in Nintendo's case, whether you need to use a stick, waggle, or swipe to control Mario.
