Less the weight than the increased size for me. Admittedly I don’t use it for very long periods so the smaller screen is less of an issue. I think for my needs it just lets me stick it in a small backpack and forget it, and I prefer the keyboard to a tablet (though no doubt someone will tell me there are fancy tablets with keyboards now!)

I have an M1 13” Air and my wife still sometimes uses my old 2016 12” Macbook (920g). Whenever I pick hers up by accident I’m reminded how noticeably thin and light it is. It seems like a small difference but it changes the feel quite a bit.