I like that OSX is not touch sensitive and like not to have finger spots on the screen
I'm also not a fan of finger prints on screens, but that doesn't alter the fact that touch screens are an extremely useful way to interact with software and having tried it you realise how handy it can be. Also having suffered with RSI in the past, anything that reduces dependence on crappy mice is a good thing.
I use the 15" retina version and find the screen big enough. Compared to the old 17" also lightning fast.
A new computer being faster than an older one, well that's a surprise! A 17" version would be just as nippy and could have room for a second hard drive too.
I like a big screen as it's well bigger. Higher res does not make the smaller screen any bigger, no matter how often an Apple store numpty tells me this. I can watch TV on my phone and it the same angle of view as my projected TV image if I hold it close enough, but it still looks small and pokey compared to a actual large screen.