SFF isn't bad as long as PC OEMs and DIY kits don't go the route of Apple and solder everything to the damn board.If I recall correctly, the first mini I tried out was one of the PowerPC ones. But yeah, the move to the Intel "Core" CPUs was a superb decision, and when they made that move I started touting the benefits of this device to friends and family.
But yeah, I kinda stopped doing that after a while. Apple took the mini (and honestly, all the rest of their desktop computers) in a direction I didn't really like.
While Apple has been turning all their computing devices into "boutique" works of art where form trumps function, other manufacturers have gotten into the game and are moving the SFF forward, as you note.
Perhaps what Apple needs to do is, just once, develop an "ugly Mac". Forget about aesthetics for a single dang moment, and produce a device that is designed to get work done, not just sit there and look pretty...
I think the next Pro is going to be an "ugly" model, just so it stays ahead of the competition. The Z800 is not a pretty machine, but it can be bought with just about every option a professional may need or want. We may see optical discs come back in the future. Research is still going on to make them smaller, faster and to hold far more data than is possible today, even with bleeding edge tech. The idea of getting everything from the internet is fantastic provided the speed makes it doable and there isn't limit in place.