So, LH2 tank engineering is not trivial. If you want it to launch from Earth, then you have to confront icing and insulation. For various reasons, this works best with a single layer of structural tank, with insulation foam applied outside that and optional paint outside that.
But this becomes a problem if you have dreams of using these big LH2 tanks for a space habitat. Bits of foam breaking off becomes space debris - a hazard in LEO.
nyrath