CATV incurs loss at every connection, so it's not really in anyone's interest to install jacks in every room and hook them up to a giant splitter, as signal quality will be horrible. Best to still install jacks to every room (and multiple places in living rooms where they might want a TV on different walls) and run them TO the splitter, but only actually hook up the jacks to the splitter that will be used. Cheap and easy to run & hook up. WAY cheaper and easier than waiting until the house is complete, no?
Phone lines are cheap and easy to wire and hook up, too. Not very professional to blank them out, is it? I know I'd be pissed if I paid $300k+ for a home and had to hire someone to come back to wire up a jack so I could hook up a phone into a phone jack...
Same with CAT5 ethernet cabling now. Biggest problem here is figuring out where to run them to
