"The average homeowner only save about $600 with the mortgage interest deduction"

Maybe nationwide across all existing mortgages and tax situations, but...

Actual savings depends on where itemizing (mortgage interest, property tax, state/local tax) puts you compared to the standard deduction and where you fall in the marginal tax rates.

If my itemized deductions are $15k, the standard deduction is $12,700, and I'm solidly within the 15% bracket, the fact that I have a mortgage only "saves" me about $345 (15% of that $2300 difference).

If, however, my itemized deductions are $30k and I'm near the 15%-to-25% tax rate threshold, the fact that I have a mortgage might save me $4,000 in federal tax.

Once you cross the threshold where itemized deductions are greater than the standard deduction, you start saving [tax bracket %] X additional interest. While the first $10k of interest might only yield the $345 savings above, the next $5k of interest might save another $750 or more in tax.