Excellent thread, Peri. My experience has been veryyy similar to yours.
I started paying more attention to fashion & style around 4-5 yrs back. My initial dabbling were with a very classic style - pencil skirts, fitted sheath dresses, heeled pumps etc and I got compliments all the time. I was going from jeans-and-tee to putting in more effort and ppl noticed that.
However, complete strangers would give me compliments too. I think everyone can appreciate something truly classic (and evergreen). And most people who aren't really into trends don't even know what 'dated' is.
I'm still young(ish) at 32. Yet, I rarely get compliments for wearing a nice outfit anymore. It's expected of me, so it's become the norm. I always get compliments (by my husband) if I'm wearing sneakers or anything sporty because that is what most appeals to him.
I'm most likely to get compliments on my hair, bag or tattoo now-a-days. But you've made a brilliant point there. If no one is noticing the teeny-tiny details of our outfit, why the hell do we fuss over them so much!!!! I think we expect so much because we want to PRESENT the BEST VERSION OF OURSELVES....because even though others may not notice or care, we care.