Add another for 3rd party TRIM support.
And yes, Apple does sell a few systems with standard HDD's. Namely, the current Mac Mini (2.5" HDD), the 21.5 and 27" iMacs (2.5" and 3.5" HDD) the new 5K iMac also uses a 3.5" HDD, and the 2012 13" MBP.
That is 5 computers Apple is still shipping with HDDs that can be replaced with an SSD.
Plus a LOT of others from years past. I have them in our 2007 iMac, 2008 MacBook, 2009 MacBook, 2009 MacBook Pro, 2010 MacBook Pro X2, 2012 Mac Mini, and many more at my office that I've done.
It's true many of the SSDs now will do garbage collection themselves, but some do not. Particularly the one in our 2007 iMac. It's an older OCZ model and it's dropped to around 80 MB/s from where it was at close to 250 MB/s. On Mavericks I had TRIM support and it was fine, not so with Yosemite. It's still fast, but not as fast.
And bug fixes. I went back to Mavericks on my Late 2013 rMBP because of all the bugs I had in Yosemite. Not waking from sleep, Aperture issues, WiFi issues (also in Mavericks however), UI lag, and more.
I was still using Snow Leopard on an Early '08 MacBook up until late last year, and I'm always amazed at how little, if ever, it would freeze or bug out. I had 3 months of uptime on it at one point. Zero issues. I'd like to get back to that.