The sleep naked "myth" has some validity. A cold sleeping bag needs to be warmed up, and a naked body does this quicker than a clothed body. (This is the same principle used to warm person with hypothermia- get in bag naked with patient.) But once you get the bag warmed up, putting on a sleep layer will keep you warmer throughout the night. By the way, to get a warm body before jumping into the sleeping bag, I take a brisk stroll right before bedtime. If I hop into your sleeping bag cold, it takes longer to warm up.
I never sleep in my hiking clothes, simply because I want my sleeping bag to stay clean longer. However, having to put on clothes every morning does slow me down a bit in the morning. Theoretically it would be nice to just get up already dressed.
I find that a lot of backpackers view the long-distance thru hikers as examples. Unless you are doing the same style (walk fast, go far, hit towns often), their equipment lists may not work for you. Each backpacking style has its own needs. Try to glean advise from those who have the same style as you do.