I don't think Excel is worse on a phone than on desktop because people don't think it's capable of "real work". It's worse because the whole interface of Excel is designed around a mouse and keyboard. The tiny little cells, the dragging things to be wider and narrower, typing everything - everything is designed around using a very accurate pointer and a keyboard. I have no idea how you'd use Excel productively on a phone. Even if the cells are the same size as they are on a desktop, the screen is tiny, so you'd not be able to see anything. And if the cells are smaller, then they're even harder to use. They actually need to be bigger to be a decent touch interface, and then you'd be constantly scrolling around.

The same applies to things like text editors. Phone keyboards are awful for typing anything except English prose. The only reason they're usable for typing is the autocorrection features. I turned mine off for a while and then you really realise how precise you have to be to type everything correctly on a phone. You certainly can't write code on them - imagine switching to the symbols keyboard every couple of seconds. It just doesn't make sense. It's bad enough typing a URL.