True. But there's no fun in that. It's like the Matrix. You could theoretically survive in one of those battery vats, surrounded by warm goo and fed by tubes, but it wouldn't be a satisfying life. You need to have color and animation and entertainment and spontaneity to thrive. Why deprive yourself of a visually and aesthetically stimulating environment on your computer screen? Especially if you are going to spend so much of your day using it.
Plus, think about it from a marketer's perspective. 2 things sell products - name recognition and visual stimulus. Which is why most people buy Windows - they've heard of it, and probably used it at work. In a computer store, with 3 basically identical laptops from 3 different manufacturers running 3 different OSs, how do you differentiate one from the other? How do you get them to buy your laptop? With wicked graphical effects and bitchin come-ons.
Furthermore, if your computer is unable to process OS graphical flourishes smoothly and easily, you are either a) running a computer that is too slow for your OS, or b) running a computer that is too slow for what you require of it. Upgrade your shit. It doesn't sound fair, but that's how the computer market works.