On the quest for tone
I agree that we (using the "royal" we here, to mean guitarists who are gear hounds, myself included) listen for things that might not matter to anyone else. I have been known to drive my wife (who is a saint) totally bonkers by playing the same riff over and over while changing guitars, amps and settings to see what effect they have. Why? Maybe because I'm avoiding real work (like learning how to apply music theory to guitar - something I never got around to in my formative years), or maybe because I'm uninspired at the moment, or maybe... just maybe because I'm learning something about electric guitar timbre (I refuse to use the terms "sound" or "tone" in this kind of discussion) from all the tweaking.
First of all, I firmly believe that the whole player / guitar / amp / room system is very complex. I think that most of us have noticed that small changes in initial conditions can produce some fairly noticeable changes in timbre. (Tangential note: Any mathematicians in the house? Isn't that kind of behavior a hallmark of a chaotic system?)
So, how do you discover how all the variables interact? You change them and see what happens! I've always done this. When I was a teenager I tweaked and modded my guitars - experimenting with setups, pickups and electronics. I also modded and built amps and effects.
Now, some three decades later I still experiment. I've taken advantage of my relative affluence to burn through a lot more gear than I ever did as a teenager. That, and I have a lot more options available to me than I did thirty years ago, thanks to the MI marketplace. I took advantage of all that over the past four years to try a lot of options that I didn't have the luxury to explore in the 1960s and 1970s. Judging from the quality of the posts on BT, I'd guess that a lot of you are in a similar situation with respect to age, experience and income.
I'm not going to argue that my time was better spent searching for gear rather than playing. However, I dare say I've learned a lot from my experiences of the past four years. I have a couple of rigs that I'm very pleased with, and I've learned - after spending a fair amount of time and money - what doesn't work so well from me.
Regarding guitar heroes... I respect the old-timers as much as the next guy. I grew up listening to Page, Clapton, Hendrix, Townshend and the rest from that generation. But their live tone back in the day wasn't always top-notch. We're lucky to have recordings and films from that era. But listening to, say, Hendrix at Woodstock or with Band of Gypsys, or to Page on the new Led Zepellin double DVD, I'm impressed much more by the raw energy of their performance than I am by either their sound or technique.
I think it's a given that guitarists of the sixties and seventies didn't worry as much about their gear as we do - they certainly had fewer choices to make. I also think it's pointless to wonder about whether low-capacitance cables and true-bypass effects would have made any noticeable difference in their performances - they made the best of what gear was available to them at the time, just as we do now.