In fact, we should probably repeal it altogether - in theory it subsidizes home ownership for the poor and middle class, but in practice the only people who take it are those who itemize deductions, which the poor generally don't.
I'm aware that interest is generally deductible for businesses, and I'm suggesting that houses should be an exception to that. We subsidize most business borrowing because we want businesses to borrow and invest in stuff, and we should have exceptions for things we want to discourage investment in. Sure, it's difficult to imagine how to keep a giant corporation from finding a way around this, but we have difficulty getting giant corporations to pay taxes generally. It would still make sense to narrow or end the subsidy to discourage individuals and small businesses from investing in RE so heavily, and consider other approaches to discouraging larger corps.
As an investor, you don't have a mortgage interest deduction benefit. You have a business expense benefit.