Ken:
"....the solid-top filters seemed almost spiteful (how could omitting a 5-cent cup made of plastic save anything?)"
What those solid-top filters were probably intended to save was sales - of higher-end models.
My first Maytag automatic was an A208, a one-speed Fabric-Matic machine. All Maytags I've owned since were at the other end of the line, the TOL A806.
With the single exception of having the console light up, the near-BOL model would do absolutely everything the TOL one would do. Softener dispenser? Check. Bleach dispenser? Check. Delicate cycle? Not only check, but Fabric-Matic did a better job on certain things than the low-speed A806 gentle cycle.
There was, in short, very little reason for a knowledgeable buyer to choose higher-end machines over lower-end ones during the run of the second series of "New Generation" machines. And word gets around on that sort of thing. Even worse for Maytag, there was not even the usual styling incentive for purchasers to get the same series washer and dryer - most any model washer "matched" any model dryer, since the console styling was so consistent. Sears didn't let you get anywhere near playing games that cost them money like that until the advent of the black-console machines.
I think Maytag's intent was to give buyers an incentive to go up the line at least a bit, so that the higher-numbered models would sell a bit better. You have to remember that there was not that huge a mechanical difference between one Maytag of that era and another, and there was not really a quality difference, so the higher-end models were probably much, much more profitable than lower ones. To keep putting all the TOL features on BOL machines meant they were giving profit away.