It's a question of market share. The fiddlers, the experimenters, are always going to be a niche market. Kobo has, for the most part, done a decent job of offering stuff to this market. The font support is a big example of this.
But when it comes to the core experience of the product, which is buying and reading a book... they're always going to pitch it to the greatest market, or, as you put it, the lowest common denominator. And the home page is a huge part of that experience.
Perhaps someday they'll have the time & resources to make the homepage experience customizable. But the more something is customizable the harder it is to support. In my opinion it will always be very, very low on the priority list. Even lower would be changing the default behaviour from what it is now.
As for buying more then five books... it's not all that easy. With Kobo it's difficult as you have to make five separate purchases. With Sony, they're encouraging "Buy Now" which also ends up with one purchase at a time. Don't know about Amazon or B&N... how do they do things? (I ask as I know we have multiple device folks around here.)
My point is that the lcd customer... the largest part of any market share... will likely be buying a single book at a time.