Andy_K 

The new Sora group stayed at 9-speeds. I guess someone at Shimano realized they could trickle down the technology without increasing the number of cogs. I think it makes sense, but I'm not sure how long they'll be able to maintain that position.

Shimano has historically made products for a customer base that didn't want to admit its own existence. The Tiagra and Sora lines have been directed toward enthusiast cyclists who are interesting in "sport" riding but aren't actually competitive racers (a nice way of saying we don't have the legs to use a 53-39x11-23 drivetrain). The current Sora page on the Shimano website describes them as "sports/fitness cyclists."

For a group like this 9-speed drivetrains and triple cranksets make a lot of sense. Unfortunately, the majority of riders in this segment seem intent on telling themselves that they need the same equipment the racers have. It's a shame because it seems like it would otherwise be possible for component manufacturers to develop new products that better served this segment instead of just trickling down racing technology.