Especially when people are willing to solve captcha's for a few micro coins at various earn free coins sites.
Yup, fools working for less than minimum wage so the bots have a library of solved captchas.
Minimum wages aren't the same everywhere, and not everyone can land a minimum wage job. (Economics 101: Minimum wages create a price floor, which leads to unemployment. Essentially, it's still better for a human to "waste time" making very little money solving capchas, than doing nothing at all.)
The logic question "capcha" seems like a good idea to me.
Justify it to yourself however you want, but it is taking blatant advantage of them and is wrong.