In some ways they are.
You might find a woman that will deny she's interested in such a ring. And years later, you'll find out she was. In other words, she's probably just being polite to you to say she doesnt care when she really does.
The ring means more to a woman than just that.
Of course they do. But every woman wants a man to show her they care. And getting a decent ring is showing you care.
Not suprising.
My wife has made no bones about it that I have to buy her a new ring for our 30th Wedding Anniversary. Its going to put me back around 5k to 7k easy. That, plus an anniversary trip to either Mexico, or Hawii (she wants to renew our vows with one of those beach thingys) and i'm 10k out. But she's worth every penny of it.
So your opinions are really just your attempts to justify your wife.