In that case, what are we waiting for?
I honestly question how much of an impact that would really have, as the increased connectivity -- especially with modern construction methods -- would, at worst, only slightly reduce property values. If noise is really that much of a concern, use Sapporo as a reference point.
At some point, we'll really need to get over this aversion to setting up elevated lines, and I say this as someone who doesn't exactly like heights.