I think it's perfectly reasonable to consider the value of your time. But time spent doing something you enjoy is *never* wasted, regardless of what the something is.

The breastfeeding thing, though, is a bit more specific. Breastfeeding isn't necessarily "free" compared to formula, and there's nothing bad or unfeminist about acknowledging that during a formula shortage when there are so many people who don't understand how lactation works saying "Just breastfeed then."