SFFPC is still too much hassle for an average builder, plus "ITX tax" is not very attractive too. I have built my first SFF last winter and I had to read that sub for a long time to find out all compatibility issues, and even then I ran into incompatible cooler mount and MB, I had to use a bit of force to set CPU cooler on a crooked mount. And latest trend of AIB GPU manufacturers to abandon 2-slot format is also not good for SFF.

Another issue are thermals. I can find out that my SSD is overheating to 105* in the nice looking ITX case and mitigate that a little (I have to hope now that 82-83* on a working SSD won't kill it too fast). Average user will see this by a blue smoke coming out of the case :)

I wish there was more initiative from big manufacturers in that area.