I really don't get why people who call themselves 'mainstream' economists can't see or choose not to acknowledge the issues the Austrians bring up. It strikes me as quite odd. Not everything the Austrian school preaches is correct, but they do have some valid points that I would expect most smart people to understand.
To bring up just a few big ones:
Printing money and low interest rate policy of the Fed influences many things other than the simplistic lower interest rate=more spending=more growth formula commonly preached.
1) it hurts people with savings. A good example is all the retirees who have saved their whole life and now can't survive on the 1% returns their savings are generating. The Fed is supposedly helping people and business who want to borrow and can do so at low interest rates.. but that does not trickle back to pensioners who should be earning more on their capital if they were not competing with the Fed.
2) monetary expansion stimulates the economy unequally across industries and geographic regions. In the models of the academic economic departments, monetary expansion may apply equally to an economy as a whole.. In the real world short run it is a transfer of wealth from one group (wage earners, people who hold cash or low yield bonds) to another group (banks, government contractors, rich people with lots of land and stocks). Some people benefit from low interest rates and new money, but many people are hurt by those same policies.
There are quite a few other issues that Austrians seems to be correct on, but these seem to be two of the most obvious to me.