Only if you need them for your specific application. According to your list up top, i dont see anything critical that does not have dicrete commands (Cable box can stay on, and DirecTV-Brand?) In this senario, no I/O's or Relays would be required.

If you change gear, you can always add outboard boxes to accomodate additional needs.

If you want to be more prepared for the future, look for a CNMSX-Av (Or Pro) these have built in Relays and I's (and more RS-232 Ports) and have an Ethernet Upgrade available as well. If you go this route, you wil need an outboard RF Gateway for the Touchpanel (CNRFGWA) The ST-CP has a built in gateway which makes it a great starter peice.