> But it also stands to ask, why isn't the bridge being constantly targeted? What factors are weighing ukrainian decisionmaking to not simply strike the hell out of this bridge until it falls?

This is a spitball, but there are several hundred thousand ethnic Ukrainians in Crimea (along with many more ethnic non-Ukrainians who were previously Ukrainian citizens and have been more-or-less forced to take on Russian citizenship since 2014). Even if the Ukrainian war machine wanted to commit war crimes and/or genocide by completely starving out a city of 2.5 million (unclear if this is true or not, at least to me), they would be -- at least partially -- commiting them against their own people.