Graphics didn't help KZ2 succeed. They didn't help KZ3 either. Not even KZ:SF. What makes you believe a new, yet again better looking Killzone will all of a sudden become an immediate smash hit? This is exactly why Sony and their studios are in such a bad spot when it comes to MP, they simply don't get it, they don't get that a games has to be first and foremost gameplay-drive, not story-driven, because in MP there are no cut-scenes, no scripts, no melee executions, it's all about running and gunning.
And the best part is they were actually so damn close to establishing their own, huge MP franchises - all KZ2 needed was fixing the damn controls instead of being stubborn fucks saying that 200ms input-lag adds "weight", and stop continuously buffing the Bots and Sentry Turrets which pushed away the loyal fanbase who could actually live with those controls. That's all they really had to do, the game was played by 2-3M people after launch, whihc in those wime was a huge number, but those two things made people abandon it. Then KZ3 showed up and completely revamped the MP, tossing in unnecessary vehicles, and with a "sniper" with full invisibility and a fully-auto assault rifle, now whose idea was that??
UC2 - amazing MP, one of the best TPP MP ever actually, and Plunder mode is still one of the best innovations and ideas I've played when it comes to MP, the game really could've been Sony's equivalent to Gears, but it was single-handedly killed off by that awful matchmaking which took 20-40min. to find players, and then when you finally got into a game it was always low-level newbie players vs high-level veterans, so not only one team lacked experience, map awareness etc. but didn't have access to one of the Boost what significantly improved the guns accuracy, basically people waited half an hour for a match only to get the floor wiped with them. And the best part? Instead of fixing the matchmaking ND started to punish people who were leaving such uneven matches. So as a result the game also died really fast. And then UC3 showed up, with even worse, more unresponsive controls than UC2, but with a remedy to the previous issues - Power Plays, a.k.a. rewarding people who suck at the game... So it dies even faster than UC2.
RFoM was actually the very first game developed for PS3 and its launch title, the MP was a typical arena shooter which was a norm back then since CoD4 hasn't happened yet, and the game had it's loyal fanbase for quite some time. But then Res2 launched and tried to (badly) copy-paste CoD, and with its 60 player MP on top of it it was nothing but a chaotic mess. Res3 was awesome, easily the best in the series and one of my favorite FPS of all times, but the game had some serious balancing issues (like homing RPG, seriously...) IG took too much time to iron out, and soon after BF3 launched and nobody cared about Res3 anymore, the game literally died within just a month.
So within just two consecutive games Sony's flagship devs showed well how extremely incompetent they are when it comes to MP mode, some of the ideas are so fucking stupid it makes you question if they even played/tested their own games before launch... And you expect those people to came up with something that'll attract a decent crowd for more than a month? Let alone replace the king of FPS like CoD? Because of pretty graphics? And believe me, I'd be the first person on the planet in the queue for a KZ2 remaster, but even I know the honey moon would end after two weeks. Like I said in the first paragraph, Sony's devs simply don't have what it takes, and making malee-focused games in the past decade didn't help them gain any experience, to say politely.