You imply that your 'internal' value of the trip is simply the function of the cash price and thus 'people would gun for the MAD'. And from this point of view F class redemptions on certain carriers is hard to compete with in terms of points valuation. If I were to choose between MAD and BOS though there's a good chance BOS would win regardless of the ticket being 1/3 the price the MAD one.

Take for example my own experience - last summer I wanted to visit Yellowstone. It cost me 60,000 miles RT ticket to get there from DFW. Following your logic I should have used these 60,000 miles to fly somewhere in Europe to get a better value. The only challenge is I didn't care for Europe. Or for Hawaii. Or Alaska. I wanted to see Yellowstone, not Iceland with a creative routing including stopovers in Europe. I saw what I wanted and have never regretted a single mile I redeemed for this trip regardless of the value.

Different people have different attitude - some with choose a destination and then try to minimize the miles to get there while some don't care about the destination as long as they get a mind-blowing c/point value. There's simply not a right answer to the original OP question.