Yes, at least one "normal" USB port would facilitate the opportunity for select apps to leverage add-on hardware. For example, there are some who want an

TV to also be a local (not cloud-based) DVR. Others want to be able to add a disc player so that it can also play disc-based media. Some want local over-the-air tuners for local HD (without reprocessing and probably over-compression to stream the locals). Some (maybe even many) want local storage so they can turn off that computer and/or take the computer out of the home and still have a working

TV for others in the household. Some want to use wired game controllers to beat any wireless lag. Etc. Companies like Elgato that already make USB tuners and DVR functionality that leverage USB hardware could deliver on such wants.
Another faction does NOT want such functionality (unless Apple decides to build any of it in and then it will be passionately embraced and one of the most touted reasons that make this a "must upgrade"

). From their perspective, it's a "why pay for something I'll never use" issue (ignoring that others may want such features... that there are more opinions and wants in the world of Apple product consumers than just their own).
So with a simple,
cheap USB port or two, both factions could get what they want. More importantly, THAT

TV would be that much more versatile in terms of the potential to evolve it in many ways beyond where software apps alone can take it. I'd personally LOVE to see THAT

TV come to market (even at double or triple the price of some "pro"-tagged version that includes some normal USB ports)... but I don't expect it.