That's the rub. Yes it wasn't a streamline design, but rather the result of a series of upgrades over the decades, but it was still producing important and mean

That's the rub. Yes it wasn't a streamline design, but rather the result of a series of upgrades over the decades, but it was still producing important and meaningful science. A full refit of Arecibo (obviously while it was still in one piece of course) would have likely been much cheaper than building an entirely new telescope.