But most of us here just don't need that level of awesomeness.
Yes, but some do and it is to them I write and for them I do the research. I fully realize that much of what I post is meaningless to those with limited understanding but remember that this forum is for "In depth technical threads related to the biology and chemistry of home brewing"
...why should anyone but scientists in a laboratory waste time and money on purchase and use of pH meters good to +-0.02?
Because it isn't a waste of time or money. All but the cheapest meters meet that level of performance now. You have to look at the Chinese toy meters to find one that isn't that good these days. I guess you can still find old stock of meters from the days of yore out there though.
All the nitty gritty science, technology, and math in the world doesn't matter if we can't taste differences.
Where the heavy research is done is in the large breweries where the object is not your taste perception but to increase profits largely through increased sales which is, presumably, effected by the way the product tastes. You can be sure that these breweries have thoroughly researched pH (and every other variable they can think of) with the object of finding ways to increase sales.
In the end, we here are all brewing beer, with the goal that it be consumed and enjoyed. Taste of the final beer is the bottom line.
As noted in an earlier post there is a great deal more to it than just this for many home brewers. The fact that you are unaware of these other aspects does not mean that they aren't important to some and you should be grateful to those people as much of the techniques that allow you to make decent beer were discovered by those guys.
Maybe this pH stuff matters a little. Maybe swings of 0.10, 0.20, or 0.30 are what really matter when it comes to final beer quality -- I am not certain of the exact taste threshold and actually I would be interested to find out what that threshold is.
For someone who is 'not quite certain' you seem to be quite strongly convinced that mash pH isn't that important, as you later state.
But, if taste is indistinguishible either way at +-0.05, then sharpening the tool to +-0.02 does not matter in the slightest with respect to the bottom line. To a scientist, perhaps. To anyone else on the planet, no.
It is the scientists (and advanced home brewers too, in fact), aware of things that you clearly are not, who have, and will continue to bring about the material and process improvements that allow you to make beer as good as you can today.
I'm not convinced that it matters in the slightest. I brewed all-grain for about 10 years without major issues until I started measuring mash pH. Has my beer gotten any better since I started measuring? I really don't think so.
Unfortunately, the only conclusion one can draw from this statement is that your palate is impaired, somehow, relative to the normal taster's. A normal drinker, at least one with some training in beer tasting such as a BJCP judge, would have noticed profound differences. I often quote "All the flavors just became brighter." as an example of the response from those undertaking mash pH control for the first time. I number myself among the many that found tight control of mash pH to be one of the most dramatic things I have done to improve my beer (with the other being temperature controlled cylindroconical fermentation).
So then, am I just wasting my time?! My current answer = Probably!
Yes, given your palate impairment, I am afraid you are. I am color blind. If I spend money on a TV set with widened gamut I am wasting that money (and the time taken in trying to set it up). Given that you can't taste the improvements brought about by mash pH control why waste time trying to implement it? Consideration for other people who drink your beer, I suppose. Whether you can taste the difference or not your beers are better when mashed with a pH between 5.4 and 5.6. Though you can't tell, your 'customers' will be able to. Just as I use electronic tools to color correct my photos/videos against things I can't see for the sake of people I show them too I think it is sort of incumbent on you to use an electronic tool to make corrections you can't taste to insure that those who drink your beer are getting decent stuff.