Because even HTTP and the server side are growing in complexity. User expectations that browsers are the outside world and the aversion to full page loads are big factors.
But a stripped down UI serves to make a non-tech savvy user not associate it with their usual browsing.
I know server software is getting complex as well, but to my (limited) understanding the interface was the biggest offender when it comes to unnecessary use of resources, which is the problem my proposition tries to solve.
