WARNING - anti Nikon rant ahead!
I must admit that Canon has really been doing the right thing ever since they changed their lens mount in the late 80s..
In the meantime; Nikon has stuck with the F mount and now we have the ridiculous situation of so many changes made to the mount that many of those changes are no longer backwards compatible. So-much for the much acclaimed redundancy that Nikon has always heaped on their customers.
No wonder so many pros have gone over to Canon.
With Nikon's silly 'Ambassador Program', it seems that the only pros using the gear are the ones being paid by Nikon to do so!
Of course, I know this is not really true but it sure does seem that way.
End of rant 
Guess I completely disagree (in a friendly way) with you
As a then Canon user with several FL lenses (the Canon lens mount prior to the FD) I for one did not think the 'upgrade' to the EF mount was such a progress
I up till then was a two system user. Had my Canon with short FL lenses set from the early 70's, got a Nikon set to complement it with additional focal lengths when i started my professional photography studies in the early 80's
(Nikon really was the pros choice in those days, not so much because of 'superior' equipment, but of a better service/dealer network, better repair options and, very important for a budding photographer, wider availability of 2nd hand gear and 3rd party accesorries)
While I could still use my FL lenses with FD mount camera's, with the switch to the EF mount they became next to worthless (and in the late 70 early 80's one didn't switch systems or bought the next new thing as easy as seems the rule nowadays)
I held on to some of my Canon FL lenses, but after that made a more serious commitment to ( and investment in) my Nikon gear, especially as I could even use my manual lenses in AF mode on my F801 and later model film SLR's
I still can use my late 70's Ai lenses without any problems on both my FE and F2AS, as well as , without any need for a special adapter, on D7100, D3, D800 and DF, and even got a couple of pre Ai lenses I can still use on my Df, with fully functional TTL light metering.
While I can still use my AF D lenses on the above mentioned old film bodies, and even some of my AFS lenses on my later model film SLR's like F90X and F100, with functioning (multi mode) lightmetering and AF
Sure Nikon has not always made life easy ( the slow slow AF of the F4 they held on to for too long, the noisy low MP DX sensors prior to the D3)
From my experience, it was in the F4 days that many Nikon users, in particular sports shooters and photojournalists, switched over to Canon, not as much as because of 'problems' with backward lens compatibilty (as said, if you were a FL/DF user that was was much more of an issue) but because of the faster AF of the EOS1 and in particular EOS1N, and the lavish premiums Canon lured pros with if they switched (pretty much like Sony does nowadays)
But many photographers shooting other subjects (wedding, portrait etc) never made that 'mandatory' upgrade, and when Nikon introduced the F90X and F5 (and F100) saw the AF 'issue' solved.
But Canon has had its share of 'oops' moments as well ( the ultra fast, but also ultra unreliable AF of the 1D3, and later 7D, the for a long time compared to post D3 Nikon sensors inferior DR and chromatic noise, the mickey mouse built quality of their EOS 300+ series)
So in the end, both brands have had their strong and weak moments, and still do.
And of course when making statements about 'pro's' switching brands (and as a grumpy old man my observation is that many asssume themselves such far too easily, just based on a website with a pricelist and some equipment bought with their credit card), one should keep in mind that nowadays there's a constant wandering of GAS motivated shooters who 'upgrade' and switch (back, see Nikon D750 and D810) whenever any brand comes up with the best next thing
