Well the more profitable computers are also more powerful...
More and more I think the Mini no longer has a place in Apple's product line.
It's goal was as a low(er)-price way for people to experiment with OS X while leveraging their existing investment in peripherals. This was very important in the PowerPC days because back then you had to replace all of your software with OS X equivalents and that meant an investment in both money and time beyond just the hardware purchase. Offering something much cheaper then the iMac or PowerMac to allow folks to "try the water" made sense then.
Once Apple moved to Intel, the need for the Mini pretty much ended. If you buy an iMac or MacBook (Pro) or Mac Pro and find you hate OS X, just run Windows on it and enjoy the style. Feel free to experiment with OS X all you want, safe in the knowledge there was Boot Camp and Windows Virtual Machines to fall back on.
I myself started with a MacBook and an Al iMac. In the end, those were mistakes because within six months I was committed to the OS X platform 99.99% (I boot into Windows for two apps - ACDSee and MP3 Tag & Rename) and have since bought a MacBook Pro and am preparing to buy a Mac Pro as replacements.
But if Apple had not moved to Intel, I would have bought a G4 Mac Mini and experimented and likely would have eventually committed to OS X since most of the OS X applications I use today were available in PPC format. With the move to Intel, the need to get the Mini evaporated, since I could replace my current laptop with a Mac and leverage Windows on it.
And Apple is not interested in making the Mac Mini into an HTPC because they have the Appletv.