this is not an engineering problem, it is a "how much are we willing to affect wild life" problem.
It's absolutely a financial decision, but it wasn't a financial problem. Cooling towers are not free but in the grand scheme of building a nuclear plant they're not expensive either (most power stations — including non-nuclear — have cooling towers).
And "Direct cooling" is not a passive option, you're still pumping water from and to the river or body of water in order to condense steam in the secondary circuit. What you're not doing is semi-closed cycling of that water through a cooling tower, you're feeding the condenser straight from the body of water, and sending water back into it more or less directly (possibly having gone through a radiator of some sort to shed some heat).
The issue here is that the body of water is "intermediate", so it was large enough the designer felt they didn't need cooling tower as inflow would be sufficient in all but extreme case, except the extreme case is becoming the normal.