Most of the time, the higher an imager's resolution, the smaller the area on the surface you can record in an image. Primarily, this is due to memory and bandwidth limitations. For example, if you have 10 meter resolution and take an image of an area 10 kilometers wide by 10 kilometers long, you're talking about 1 million pixels. If you're using 256 shade grayscale, that's a raw image size of approximately 1 megabyte. If you use color, then you're typically talking about 3 or 4 bytes per pixel for the raw image. Now, if you bump that resolution up to 1 meter, you're talking about 10,000 x 10,000 pixels, or approximately 100 megabytes per image for grayscale. With higher resolution, you can reduce the size of the ground area covered to reduce the bytes per image. JPEG compression can reduce the size of that image considerably, but at the risk of lost data.

Mars is a long way from Earth, so you need a high signal-to-noise level on your comm system to achieve a high data rate. To get that, you need a fairly powerful transmitter and a really good high gain antenna, typically a good sized parabolic dish. The higher the antenna gain, the smaller the beamwidth so your pointing requirements become more rigorous.

I, too, look forward to seeing really high resolution images from Mars. Just keep in mind that the really high resolution means the percentage of the Martian surface imaged will be smaller. MGS has much higher resolution than the old Viking orbiters, but it only has enough memory to store a few images per orbit. After all this time, MGS has only imaged a small percentage of the Martian surface. The new orbiter will probably image an even lower percentage than MGS, but the results will be spectacular.

I only hope that NASA doesn't waste any time trying to please the Mars Anomaly crowd.