While I totally understand what you're saying and agree with you, I've had 2 of the 85W Mac power adapters replaced out of warranty (2012 rMBP). I'm a "road warrior", travel around 250k miles / year, probably pack / unpack my computer 4-8 times per day, and I'm good about winding/unwinding the power cord, but it's just not designed for that kind of wear & tear.
I think I've gotten replacements because I've been able to show the electrical arcing that takes place (for anyone reading this who doesn't know what electrical arcing is, look it up). Between the nice spark, the sound and especially the smell, employees are pretty damn quick to replace the part. (I did have an employee initially try to just replace part of it, and when I showed him how the problem remained, I just walked over and grabbed a new one off the shelf and told him "I'll just take this." He scanned it and off I went.)
FWIW, the problem I'm talking about is the little 2-prong AC adapter that slides on to the main power "brick". On an 85W model at least, all that weight is borne and supported by the connection, and the torque (or maybe I should be using a term like "lever" or "moment", I don't recall my physics very well) is too much over time.
Last comment - generally I just take Shoe Goo and goop it over the weak strain relief where the cord emerges from the brick. Sure, I don't look cool, but that part of the power supply doesn't fail.