CX has appeal in certain situations. For instance here in Germany (and other places) there are miles of farm tracks that are accessible but you'd end up doing lots of road too. And in places like the Beacons you can ride up a road, through some forest fire-road traffic free and then back home again - less techie, quicker and more chilled than an MTB ride. I don't own one mind.
Bar ends are great on flat bars, which are great for mile munching.
40lb freeride bikes need granny rings - winching them up hills is better than pushing them no?
Tubeless makes a big difference to rolling resistance. Made my Patriot much quicker and hence much more XCable for riding in in the hills without compromising anything on the downs. And they do seal punctures.
29ers roll really nicely, which makes them lovely and zippy on certain kinds of terrain. You can keep up the flow on the rougher stuff in a lovely easy kind of way. It's nice. (I don't own a 29er)
I don't see the appeal of bikes for bikes sake either - how can you have more than one bike that's designed for the same kind of riding?