Steven Davidoff is dismissive of money market mutual fund industry complaints that proposed reforms would "require complex accounting and tax record-keeping by investors." Speaking personally, given the minuscule returns money market funds are paying these days, I probably would stop using them and just leave my rainy day savings/cash flow management funds in my checking account rather than trying to deal with headaches come tax time of having a constantly fluctuating NAV. Who wants to deal with paying taxes on, say, 10 cents worth of capital gains because you sold 1000 shares at $1.00 and had a basis in those shares of $0.9999? And what if you want to use actual cost basis instead of average cost basis? Maybe it'd be worth doing if you're a billion dollar institution, but my guess is that a floating NAV would drive retail investors out of the money market industry.
The adverse tax and accounting consequences, as well as the capital market consequences of driving retail investors out of the commercial paper market, seem an awfully high price to pay because Congress is to fraking chicken to tell voters that it won't bail out mutual funds that go bust.
Update: I am currently invested in a California tax-exempt money market paying a whopping 0.02% average annual rate of return. That probably doesn't even cover the opportunity costs of transferring money to it from checking. How high a return would the fund have to pay to justify the costs (both real and opportunity) associated with a floating NAV? At least enough to pay for a TurboTax program!