Why does the Long Haul Trucker have vertical dropouts?

Surly bills the Cross Check is billed as a jack-of-all trades frame, accordingly spec'd with horizontal dropouts to accomodate internally geared or fixed/ss hubs. In my way of looking at things, the LHT is actually a superior rig overall as a flexible base for loaded commuting or touring applications, thanks to the lower center of gravity, wider wheelbase, longer chainstays, and more options for mounting goodies.

But the vertical dropouts have me stumped. Weren't these originally invented as frame geometry changed and wheels migrated ever closer to the seat tube? The long chain stays on the LHT leave ample seat tube clearance and seem even better suited to horizontal dropouts than the CC. Is it fender-friendliness (I run fenders with horiz dropouts, but I see why vertical could be preferable)? Or maybe it's really not all the commute-friendly as I'm thinking, and most tourers would be set up with a rear derailer anyway?

Just bummed that what seems to be my otherwise ideal frameset comes up short. I'm hoping someone can explain the logic and make me feel better about the logic behind the now nearly universal vertical dropout.