I believe you are wrong somewhat. The 5D, when in full auto mode and ISO Expansion set to ON, the ISO will vary depending on need between 50 and 3200. It does not have this feature outside of full auto. I have not used this feature given the nature of my work.
I understand your point about the Nikon feature except that you assume all DSLRs are designed for the same purpose----to shoot action where shutter speed priority is most desirable. However such features are of little interest to me. MPs, noise reduction at long exposures, availability of TS lenses etc. are most important to me. Canon, hands down, is best answering my needs. Could I do decent work with a Nikon? Of course, though there would be some compromises.
See my point? These broad generalizations about Canon vs. Nikon vs. whatever don't really shed much light except in relationship to specific usages.