I find a UL Exped nestled into the hood of my sleeping bag is very comfortable
A perfect example of my one and only point, we all have different comfort levels and many of us choose to carry a few extras because we want them. Not because they are poor/ uninformed/ cheap gear choices, as ul proponents often seem to imply. I have that pillow and I find it to be the least comfortable of the three I have. The cheapest and heaviest one is the I use on most trips.
Same with my sleeping bag. My winter bag is a Sierra designs backcountry bed 800 fill down 20 degree bag. For the same price I could have bought a traditional down mummy bag that weighs more than a third less. But I'm a side sleeper and toss and turn, and this is the only bag I've ever owned that I don't get tangled up in. It's really awesome and anyone who hates getting tangled up in their bag three times a night should try one out.
So these are examples of reasons I, and I imagine many others aren't as ultralight as we could be if we sacrificed our comfort, we all have different comfort levels and most of us fall towards the middle of the spectrum.