you've only got to look at mickysoft's windows to see that they're gradually dumbing down everything for the mass market. In windows things have been hidden from the user to such an extent now that with win8 there's even no start menu anymore.
Developers have to do what they're told even when they know it doesn't make sense. There's probably a focus group somewhere that thought greyed out options are more confusing than not having them in the first place, i.e more people would think their box has a fault or there's something wrong seeing greyed out options than when there's nothing at all to see.
It's debatable whether having greyed out or no options is a stupid omission; however the box certainly does have more pressing problems. It's frustrating though as I think we all know what an ideal box would look and feel like and we don't know why Humax can't produce it.