Personally if the developers are working to their own set of standards, like they have an upper limit for how the image quality is meant to look and that's achievable across PC, PS4 and Xbox One then that's fine. As far as I'm concerned developers can do a lot more than they have been with all platforms, they should be pushing their engines further and optimizing better across the board.
I'm sure if Rocksteady were able to achieve what they showed at the last Playstation event on all three systems everyone would be over the moon.
As far as this comment goes graphics usually relates to Image Quality, resolution can help make the IQ shine through and of course frame rate is performance, so this comment may just relate to the image quality of the game, not Resolution. The XB1 and PS4 versions can both be 30FPS have the 900p-1080p gap, PC 60-120FPS or even beyond and run at 4K or whatever and devs are still taking advantage of the differences in hardware, while keeping graphical parity.
People should bare in mind that if a developer says they're aiming for parity in some area, they're only saying that they're aiming, it's not an outright statement of fact, that the game will definitely be exactly the same on all platforms that it's released on.
