Why itx generally more expensive

[pomkon]

Than matx 

is there not fewer features?

What about itx cases?

 

matx generally the cheapeast?

[Jurrunio]

Mainly because mITX is the smallest form factor. Just like how the fastest CPU cost significantly more than something mildly slower, having the best means paying the most

 

Also difficulty of manufacturing as everything are so tightly packed, and the use of more expensive and efficient components as cooling is a problem with cheap but inefficient parts.

[BlueChinchillaEatingDorito]

Would also add in that engineering such boards is more of a challenge particularly when it's a high end board with support for overclocking. There's only so much room to fit in all the required circuitry and components to support such features. Which is why some add on sister boards for VRMs and etc. 

[RobFRaschke]

In addition to the reasons above. They often require more PCB layers in order to get everything on the board that they come with. And they're the lowest sales volume product, so the engineering and manufacturing set-up costs are distributed across a fewer boards.

[AskTJ]

Mini ITX boards would be the most expensive as they aren't purchased as often, and require lots of engineering to get all the circuitry to work, while keeping the features of an ATX board.

[ARikozuM]

‘Cuz people still buyin’ full towers. /s

 

Complexity of the circuitry, offset of I/O, and market demand all drive the cost up. Though the price is largely the same, value has gone up tremendously. You used to pay $100 for a board with two USB ports, a VGA/HDMI, one Ethernet, and a PS/2 port. Today, $100 gets you WiFi, 4 or 6 USB ports, HDMI or DP, and possibly two Ethernet.