Like many things which have a range of attributes, it all depends what you want, how much you want to spend, and what you want to achieve.
If you stick more pixels on the same size sensor, there are benefits and costs.
If you want to take snapshots, 2Mb jpegs might not be ideal. I know a few people who have a devil of a time getting image files to an emaile-able size, notwithstanding my patient tuition.
(A friend of my sister was very proudly declaring that he could get some huge number of images on his 256 Mb card by taking 640x480 size shots. Lots and lots, although kinda blocky
)
Sales people want to sell stuff, and a surprising number of people do far too little research. So the sales person says whatever will get the punter to buy whatever they want to sell.
It's just the way of things.