Portability can be taken in many different forms. For me, something that is portable would have to be a great size which is the 13", but also has enough bells and whistles for me not to worry about needing something else. For example, if I wanted to transfer something to my external, firewire is better suited for me than USB 2.0. Don't give me crap about Thunderbolt because there isn't much peripherals out there that is worth the cost for using the technology. Also, maybe I need an optical drive somehow? You never know, but I've run into quite a few situations where I needed a CD drive and I am definitely not carrying another item, SuperDrive, with me. Also, many college dorms or places need the Ethernet jack for internet because not all dorm buildings utilize wireless. I find that ethernet does have a more stable connection than wireless too, in my personal experience.
I like the fact that you can upgrade the internals of the MBP too. I currently use an Intel 510 SSD in my MBP. Pricey it is, but the speeds on aftermarket drives are proven to be faster than the ones Apple provides. I believe there are a few threads here that explains that.
Oh, one last thing. What's the point? My money, my choice. Don't like it? Oh well too bad.