4X USB 3.0 + 2.0 USB on rear is all I need. It is impossible to use eight USB 3.0 in one moment. And I have no idea why there are two LAN ports. USB + BT costs 26 USD.
Sure, there is good reason for the number of different board makers, as each will have an audience no matter the function. To me, the difference in function and the parts used more than justifies the added cost. You are right, you don't NEED to spend so much, but at the same time, you don't NEED a HTPC.
With less functionality, the AsRock board you linked is a lesser product. It also has a lesser cost, so that's cool. That doesn't mean the ZOTAC board is bad because of it, it's just different, and that difference has a price.
Maybe the VRM on the AsRock board draws more power, and then cost of ownership and usage is higher....
LAN ports, to me, are good, as well as required. Many TVs and such have network ports and such, and the ZOATC board has the ability to act as a wireless access point for the TV, or other net-enbabled devices, such as bluray players. TV and Bluray player net-enabled, means that AsRock board cannot support them all., even more so, since it doesn't have wireless.
The function is there for a reason, IMHO. If you want more out of your HTPC, the ZOTAC can do it. The Asrock, simply, cannot.