Aesthetics is important, but, in some sorts of systems, it has much lower priority than other non-functional requirements, like overall speed, maintainability, testability and so on.
I don't know if my experience is the same of most of you, but I've seen more and more systems getting aesthetic pleasant but painfully slow and/or buggy these days. It's easy when you can simply quit using the software, but when your bank, your broker, your airline, your accountant, the company that operates the subway ticket machines, when those sorts of businesses start to embrace such vision, things start to get complicated.
And, unfortunately, all those examples I mention here are real and this is not an exhaustive list.
Besides, I'm not sure those companies (at least the ones in my examples) do that as an attempt to exploit users. I believe they do that due to plain lack of competence.