Better graphics = better sales = developer has more options to have better gameplay. Graphics & gameplay often goes hand to hand ( there are exceptions) since a developer must first sell their game to the publisher before the developing even starts.
Also sometimes better game play can equal lower sales as in Vagrant Story for example.

I think 30-40 fps is enough. Better graphics can make the overall experience better and push the sales harder, t's a better thing compare to framerate.

There is a point to this. Yes we would all love every game to be 60fps fixed, but better graphics sell a game moreso than better framerate. If you look at Killzone 2, Uncharted, Uncharted 2 and MGS4, they were all 30fps max but have the best graphics of this generation so far (on the PS3, so to stop a flamewar).

I'm not sure what R2 had for a framerate, doubt it was much more than 30fps at times, but R&C is 60fps and really isn't required, especially if you can push the hardware that little bit more in the graphics department.

Thats not to say that R&C looks bad, it looks great, but it seems that developers apart from the PD's of this world with car sims really need 60fps and maybe your Tekkens and Soul Calibers, but every other genre really only needs a fixed 30fps or as close to that as possible.

It means that developers like Insomniac can say straight off 720p @ 30fps and then dedicate everything else on the upping the quality of the visuals as long as they adhere to the res and framerate.

They made the perfectly right decision. Like someone above said, it's strange it took them so long to find out.

30 frames per second is perfect enuff. 60 fps is usually a waste of resources. 60fps is only needed for car games and the online part of shooters.

Why they can't make game with 45fps? It would play smoother than 30 but you could use better graphics than with 60.

60 fps is nice when you can get it and it is more important in some game genres but in the end consistency is the key.

I do love me the buttery smoothness of the Metroid Prime games though.

Video modes of displays are usually a multiple of 60hz, ie they refresh the screen 60 times per second (or 120). The graphic triies to be a submultiple of this number: with 60 fps you push one frame per vertical refresh, with 30 fps you try to push one every two refreshes. If you go out of sync you get screen tearing because a single screen refresh gets part of a frame and part of another.

If you chose weird fractions such as 45fps and still wanted to avoid tearing you should do something like frame/frame/frame/pause / frame/frame/frame/pause/ ...  where each step is a screen refresh. This way you end up producing frames only in 3/4 of the screen refreshes ( 3/4 of 60Hz gives your 45 fps).

But, and it's a great but, this framerate is not uniform as you have three close frames, then a longer pause, then another three close again etc, It would produce visible jittering in animations, scrolling, camera pans etc.

Thanks for explanation! I have always wondered why they must lock game with 30fps or 60fps.

I think a bad framerate affects both looks as well as gameplay, I don't think they intend to resort to a bad framerate.

A great looking movie in 24 frames per second (cinema) is still a good looking and fluent movie compared to a 100 frames per second version. I think most people won't notice much of a difference.

Horrible. Bad framerate ruins gameplay - I agree that better "looking" games may sell more, but they are actually worse games (as they play worse).

It does depend on the game though.

Gimme 60fps locked anyday (i.e. FZero) and work the gfx around that.