Pretty interesting. Sort of the type of business model that those INSEAD professors who wrote Blue Ocean Strategy have an obsession about - the company sells totally unoriginal products (TOMS are admittedly a direct copy of a traditional design) but grows rapidly at what I'd have to guess are high margins and very high returns on capital bc they are clever on the demand side and found / created relatively uncontested market space. In contrast to most footwear co's, their ad spend is probably very low bc the shoe drop / philanthropy side of the organization basically generates the advertising as free publicity.
Clearly the high margins and returns on capital due to the philanthropic element are what don't sit well with people, but what's the alternative that would be preferable - TOMS takes lower margins (eg by giving more free shoes to shoeless kids per shoe purchased or spending much more on construction / materials) voluntarily? To spend more on construction would probably be counterproductive past a point - kids outgrow shoes quickly and donating something basic and utilitarian, not prized or potentially the target of theft, is probably more efficient. They do supposedly make a point of trying to identify groups of children that they can work with on a repeat basis bc the recipients outgrow the shoes in like 6 months.
And if people would prefer they give away more shoes, that's nice, but it's sort of a vote with your wallet situation. By making some kind of humanitarian instinct into a fashion symbol that people can purchase, they sort of earn the right to make whatever profit on that they can and, to the extent they want to reinvest those profits in something philanthropic (more shoes or something else entirely), that is more or less their own prerogative (as it is any business owner's prerogative to give away profits or keep them). If the business grows to a scale where it is, or appears, too profitable, there is probably a trade off between undermining the "brand" and lowering the returns, so at some point they probably have to demonstrate they are continuing to grow the philanthropic side seriously enough the keep people who buy the slippers feeling good about themselves and about the company.
I think the demand for looking like humanitarian, compassionate people without taking too much independent initiative is sustainable and probably going to be a source of profit opportunities for a long time. Whether TOMS shoes are too faddish to capitalize on that for too much longer is, I think, trickier to forecast.