1280X720 60FPS and 1920X1080 30FPS aren't really the comparisons that people should be making because 60FPS is 2X the pixels per second compared to 30FPS, where as 1080p is 2.25X the pixels per second compared to the game running in 720p.
A better comparison at equal the level of demand would be a resolution higher than 720p at 60FPS vs 1080p 30FPS.
It depends entirely on the game, in an open world, slow RPG or turn based game then the lower frame rate wouldn't be as jarring in a direct comparison, but in fighting games, racers and fast paced shooters or games with way more fast moving action on screen then I would say whatever is achievable at the highest possible resolution at 60FPS is better, somewhere between 1280X720 and 1600X900 at 60FPS would be a better comparison.
Another factor is whether it's a locked frame rate or a fluctuating one. Personally I'd prefer a locked frame rate, even if it's lower than a wildly fluctuating one with higher peaks, regardless of the game.
Hell last gen Halo 4 was only 30FPS, but it was a rock solid, unwavering 30FPS, that with the benefits of a far higher native resolution, that well and truly fills the screen is a much better option for me.
TBH though it's down to the developers exactly where they want to use the resources on the hardware they're building their game on. Vote with your wallet, otherwise IMO you wouldn't tell an artist to change how sharp they make the lines of their painting, it's their invention, they made it, if you don't like it then don't buy the game, just like you wouldn't buy the painting if you thought it had too defined lines or something of the like.
