I purchased covers because of the clanging and didn't feel the contact would be good for the clubs.
I understand what some are saying here about the abuse clubs take when hitting out of many certain ball lies.
I had a set of clubs that I used (off and on) for 15 years and it really didn't seem to effect them at all. I golf maybe 3 times a year on average so I'm sure that played a big role also.
I like the suggestion here to put the covers on when they are in your vehicle(cleaned and dried), and take them off when at the course.
Sounds sensible to me.
The covers I did buy this year are neoprene and after having golfed 4 times so far(lol, I'm catching the golf bug...look at me go), they are falling apart already.