Well to put things into perspective, tomorrow I am going to pick up a Movado watch that I had sent back to the factory to have them go through it and do their maintenance on it. They changed out the seals and cleaned it inside and out. It cost me $300.That's really cool of them and really above and beyond. Plenty of companies will get your gun like new for you, but it would cost you. Depending on the condition, I know a Kimber could be refreshed for under $200 for a full checkup that will automatically come with replacement of small parts. Once you start needing a new barrel, refinishing, etc, you could easily be in half the value of the gun to get it back to new.
Still, refinishing and rebuilding is one thing, but reliability issues are manufacturer defects and are unacceptable and ought to be fixed for free by any maker. My Ruger SP101 .22, for example, would get a lot of misfires. Like 1 every 2-4 cylinders. Someone else might have written it off as .22s just not being all that reliable. The fact is that the hammer was very sloppy with lateral play, so it wasn't striking centered at all, and to boot I was getting a lot of lead shavings spit back at my face because the cylinder wasn't lining up perfectly with the barrel. I called their customer service and sent it back. They fixed it and sent it back to me how it should have come out the factory. I would have sent it back again as many times as it took to get it fixed, replaced, or my money back. Gun companies know not every gun put out will be perfect, and that's fine. They also allow some extra degree of slop knowing that not everyone who doesn't get a perfectly functional gun will send it back and will accept some issues, and that's not fine.
I guess Glock does this in part because they want the old parts back because they study and examine them to help with future designs.