Thank you for posting that!
From 1987 until just a few years ago I thought Canon made a big mistake and I didn't like their cameras or lenses since then ('what, no aperture ring!?"). I've since reconsidered.
Nikon has done a good job maintaining compatibility between 1959 and today (more accurately. 1977 and today), though it seems the best Nikon body/lens compatibility is always within a 20-year sliding window of time (e.g. an an F4 can use NAI lenses in stop-down mode, can use AI lenses ok, can use AF-D best of all, and can use G lenses except for Aperture-Priority and Manual modes). Maybe for the working professional this was their best course of action.
Canon, however, totally pissed-off a lot of pros and people in 1987 by creating the FD/EF barrier. Looking back, I now see this as a risky but bold move. Clearly it worked out well for them. It is amazing you can take any EF lens from as far back as 1987 and use it with full functionality on any Canon camera today (EF-S bodies excluded). Likewise, I can grab an old EOS-650 and use any EF lens made today. As for quality, many of their lenses feel chintzy to me, but they work. My favorite is their cheapest: the 50/1.8 II - amazingly sharp!