But the problem with the dismissive attitude toward the McDojo is that it doesn't really matter what type of martial artist these schools produce. There are a great many people that are much more interested in the trappings of the martial arts than they are in the actual techniques. These are the people that happily attend your corner McDojo. If the McDojo wasn't there, these folks would NOT be in a difficult school struggling hard to learn solid technique. That's not what they're after.
As far as I'm concerned, it's far better for these folks to attend the corner McDojo and learn nothing of any real value than it is for them to stay home and watch reality TV on the couch. Also, it's better for them to bring their kids in to learn nothing of any great value than it is to leave the kid sit in front of his video game. Those that really want to learn will figure it out and move on to a better school.
While there may be some truth in what you write, I think that for MOST, you're wrong.
I think the vast majority of people who study MA do so because they want to learn martial arts. Not martial cardio workout. But because they (duh!) lack any experience, they can get sucked in to a school that teaches "nothing of any great value". And because they lack any experience, the fact that what they're learning isn't useful escapes them, for quite a long time. By the time it begins to dawn on them that they're learning garbage (if it ever does, since they may not actually be doing anything that would show them that their "skills" are worthless) they've got a large investment of time and money.
Will they go elsewhere? Maybe. I think they're as likely to become disillusioned with martial arts in general and simply stop training.
If someone wants to offer martial-themed day care, then fine. If they want to offer martial themed cardio workouts, also fine. But when the training is presented as actual martial arts training, then it really ought to be something of value. The typical McDojo isn't likely to offer much of real value.