Robert, it's for silly reasons. I sleep on the right side of the bed. I frequently do work in bed. Every charger I've ever had that is for a Mac that can only be charged on the leg side, has had a very short life due to the tension on that bend. My office is the same - old building, outlet only on right and no room for devices on the left of my desk. It's only a matter of convenience - but if I'm dropping 1500, the ports on opposite sides is just a very convenient convenience.

Heck, I would even be ok with 1 port on each side! I rarely, if ever, even need a dongle...so all thunderbolt doesn't even bother me.
I'm pretty sure I'll upgrade this year, after they're released. I can deal with the ports on one side.
At the end of the day, the fact that for the most part, I feel more productive on my iPad/magickeyboard is saying something.
Oh! I almost forgot. I'm a big shortcut user. Closing 3 tabs instead of 1, after ending in a client's insurance information, due to a sticky W .... huge bummer.
I miss my late 2013 mbp. I can't believe I'll be upgrading this quickly!