Actually sales numbers only show just that, sales numbers.
Do you think WoTc know the ratio between all D&D players vs how many are buying these AP's?
The answer is no they don't. Also, they don't know what new players would buy had they been given the option.
I don't think it's relevant, nor are they ever going to be able to determine the answers to those questions.
Instead they have business projections and goals based in part on earlier releases. As long as they are meeting or exceeding those goals, it's a success. What other people "might have bought" isn't really relevant.
Their job is to make stuff people will buy. Mission accomplished.
That doesn't mean they can't or won't look for other opportunities. But their strategy has been spelled out in detail several times in the last couple of years. Two APs a year, with some new game material as well (spells, races, class options, monsters, rules options, whatever). They said that was the plan, and they've followed that plan. The fact that they are still hitting or exceeding their sales goals makes it a good plan and a success.
Now they've started supplementing that once/year with an additional non-AP book, plus I keep reminding everybody that they do release a dozen or so short adventures via DMsGuild that tie into the AP.
You may not like their business plan, fair enough. But it's certainly not a secret, and they have stuck with it and I don't think, considering the success it's had, that it will change. To tie it back to your original post, they aren't "shoving APs down your throat," they are simply following the plan they announced way back in 2014.
The question is - what might be the next non-AP book release? And will they move to two non-AP books per year?
Note that a few things from UA have already made it into published books, I expect that clues may be found in the UA articles in the next 6 months or so.