Thanks for those thoughts, Jonathan. :)
IMO pickups work like a filter, and you have to take the characteristics of the timbers and the nature of the pickups filtering into account when thinking what the result will be
I agree with that, absolutely. And of course it works in several ways - you'll primarily want to choose pickups that work
with the characteristics of the timbers to produce a nice balanced tone; but you might also want to choose pickups to emphasise "good" characteristics, or try to minimise the effects of "negative" characteristics. Ultimately, though, if you don't like the tone of a certain timber I don't think you can "defeat" it with pickups - better to buy another guitar!
I see what you mean about putting something warm and middy in ash - I guess the same might also apply to a semi, as they also tend to emphasise lows and highs acoustically.
In a way, on that basis, it almost seems counter-intuitive to put single-coils in ash guitars, since they're
not really warmer sounding pickups. But I guess because they're much thinner and brighter sounding, they're never going to get flabby or boomy in the bass. And in a way, with single-coils generally I think the tone is "more wood, less pickups" as compared with humbuckers.