JoJo said:
"Girls don't buy the toys"
Well, there's your problem. I guess they're thinking that a show which attracts a large female following might also be losing a certain percentage of their male viewers who are being turned off by the same content the females want, and since the boys are more likely to buy their toys, that's potentially revenue lost. Impossible to know without the sales figures whether that line of thinking is right or wrong but it's understandable, at the end of the day their job is to make money for their company, not to advocate gender equality.
Wait, you've lost me here, how is it understandable that they think an increase in female viewers requires a proportionate decrease in male viewers, that seems like a massive logical disconnect that would require the executives to be making leaps in logic without any real evidence, they have the numbers breakdowns by gender (although demographics numbers are hardly 100% correct so they are making educated guesses about the numbers at best), the show was apparently popular with boys as well as girls, and families too, but they canned the toy line before even trying so they have zero statistics on who's buying the toys as it is.
More on topic with the OP, I don't think I buy the "girls buy less toys" excuse to begin with, the numbers of boys buying action figures has been dropping dramatically as they gravitate towards things like gaming and electronics devices, the amount of money girls spend on dolls is actually higher than the boy equivalent. Not to mention part of the reason may be because they don't make toys of any of the damn female characters. Seriously, look at most superhero toy lines, even if the adjoining cartoon or show has female characters, even popular female characters, they don't make any toys of them, or the few they do make are collector's models targeted at adult nerds with disposable income.
They don't even bother to try, yet other companies have had success with this very thing recently from both angles, Lego discovered that their Harry Potter and LOTR sets and the spinoff Lego video games were attracting female attention, so they nutted up and adapted by making their marketing more gender ambiguous, as well as rolling some of their newer sets out with much less gender targeted advertising, and they seem to be succeeding with it. They still have sets targeted at boys and girls (and the girl sets are still usually in annoyingly bright pink packaging), but they didn't run away screaming when they found out girls were interested in their product either.
On the flipside, Hasbro didn't lose their shit when they found out boys were flocking to their new MLP incarnation, they also didn't assume that male viewers were taking a chunk out of their female audience. They didn't run in fear of their unexpected audience, they exploited the hell out of it. "What? males aren't interested in the brushable hair dolls targeted at the little girl demographic? Fuck that, hold them over with some shirts while we make molded figurines and vinyl collectible figurines, and license a Magic style collectible card game while we're at it (yeah a google search reveals that is apparently a thing that exists now)". Seriously, they even went so far as to make the packaging black and dark purple for some of their sets, which sit on the pink isle right next to the Barbie dolls and pink crayons. If my weak ass google-fu is worth anything, this plan has apparently worked extremely well with the toys selling well, and the number of girls buying them going up along with the accidental periphery market. To bring this full circle back to the comics arena they are producing MLP comics now as well, which are doing extremely well for anything that's not under the DC/Marvel umbrella, and even seem to be outselling a number of DC and Marvel titles. It also doesn't seem to be just sweaty male nerds buying these things either, it's apparently popular enough in the young girl and family demos that the publisher IDW, seems to be brokering a deal to get them sold in supermarkets, a la Archie style comics.
Ugh the whole thing just smacks of laziness and cowardliness, they don't know if they can succeed so they would rather just not even try. I get that they shouldn't be required to take the risk, it's their money afterall, it's just disgustingly cynical to see something popular with passion behind it get canceled just because some business suit released a prediction model that said they had a lot of girl viewers, and then jumped immediately to "girls don't buy action figures" rather than even making an attempt at adapting. What's even more sad is they probably lost money canning the toy line before it was finished, all based on speculation and assumption.