I don't feel building a Cathedral is a venture that warrants sparing any expense. We are, after all, called to give God our best; why not go all-out with the architecture dedicated to the worship of Him?
That said, we are also called upon to be good stewards of what God has entrusted us with, and the Cathedral as designed is a tacky waste of money. Those responsible ought to be ashamed to have such a deliberately and purposelessly ugly object consecrated unto God. I'm pretty sure they can build something MUCH nicer-looking with the same or less money.
Helping the poor is a venture that warrants sparing no expense.
Worship of God is an activity that can take place in a tent or under the open sky.
God already built his Cathedrals -- the Universe and the planets.