It is not just that they are moving to glass, but that on the first revision of any new hardware design, Apple tends to have more problems than they do on subsequent revisions, so it is well worth it to get a full 3 years of coverage to last you through any problems that may, though hopefully won't, come up.
For reference to put its price in perspective, my keyboard and trackpad went belly up not to long ago and had to be replaced. The parts alone cost I think it was between $120 and $150. Thankfully I was still in warranty, but that is a decent chunk of change by itself, and if I needed more repairs then it would have paid for itself. Likewise I think the last time I looked at it, the price to replace a dead DVD drive on an old iMac that I bought(Was a display before I bought it so don't assume Apple's have significant problems

) by itself paid for an applecare plan at the time I was looking at it. I had a choice of either buy the drive, or buy the applecare extension for the same amount and get another year of coverage.
Of course I chose option C. I am to dang poor and can't afford either

Haven't really missed it, though I specifically got that computer at a good price and for an express purpose of using as a dedicated playback machine for shows I design, so the drive wasn't a huge issue.
Seablade