All fabrics wear with age. I've got a few pairs of flanny pj's that have done both older boys that I've dug out for Caleb and they are noticeably thinner than new ones.

The BBH won't be as soft as brand new but as they loose that fluffy softness they get more absorbant and they dry quicker. I noticed that when I got a couple more after having used some for 6 months.

Just be sure that you don't use the vinegar too often as it's no good for elastic.