I think that as time has passed we've had to face making certain things less important, at least as far as using up space in our memory is concerned. If I have my phone numbers stored in my cell, my home phone, a paper copy in a notebook and on my pcs, then I don't "need" to remember them myself.
.... of course I'm sure we've all been faced with that one moment where, none of those things are available to us and we try, usually in vain, to remember the number of the person we're calling.
Is that stupidity, or just mental busy-ness which takes up so much "space" we're unable to fit in the rest? As an example, I can tell you my first phone number (476-3584), my grandma's (9683585), the numbers for school, my first jobs, my earliest friends first numbers... I cannot tell you my friends numbers from now. Not even one of them! I Do remember my bosses number, but only because when I misdialed it, I'd get my prior boss and that was a no go
I can quote you the statistics for the caseload breakdown in my area, the state as a whole, the phone numbers of the IT folks I deal with, their names and office locations (and in some cases their home counties). I can tell you who works where and for whom in all 4 offices and 3 outposts here. I can probably give you their sign on numbers for one of the state systems and most of their email addresses here.
To me, these things aren't more important than "real" life stuff... however, they do keep the hounds of hell (aka bosses, people up on yon high, bosses bosses, etc) off my back...IF I remember them... So, I do.
Maybe it's just the way that corporate life has made us think that the "Job" is all, and anything else is just (or should be) a minor annoyance. Again, not really true, but something the yuppy generation agreed to, so we're all kind of stuck with it.