Ed, I'd like to use a different word than "justification". One can take the, let's say, Diehard position that any mutual fund should only have one expense ratio. (But that's no longer strictly true at Vanguard, I believe. But that's a digression.)
Without taking a political position, let me offer something in the way of an "explanation". Once upon a time, TIAA-CREF was in a large but sleepy business of running 403(b) plans for everyone in education who wasn't a state employee, and some other not-for-profits. They had no competition, and all of their funds were structured as rock-bottom cost Variable Annuities. That's because they started out 90 years ago with TIAA Traditional as their only product, a variable annuity. They didn't have to report to the SEC because they were only selling "insurance" products, regulated by state agencies.
In the 80's, faculty got smarter and more demanding, and objected to having to (only) annuitize all their investments at TIAA-CREF, and not being able to get more than 10% in cash when they retired. The mutual fund industry smelled blood (and cash) in the water, so they joined the NEA and the AARP in their action against TIAA-CREF.
When the dust cleared, TIAA-CREF started some retail mutual funds and registered the CREF variable annuities with the SEC. Those retail funds were cheaper than everything else TIAA-CREF offered, and were unsustainable. They were also dismal investments with very short records to advertise.
Today, TIAA-CREF has lost between 10% and 50% of the business it used to "own", and the field is wide open. Luckily, the "field" has increased in total size, with state tutition funds, 401, Roth, and other retirement investments. This industry, with few exceptions, like the "old TIAA-CREF" prices mutual funds to reflect the market, the needs of the customer, the degree of "captivity" of the customer, and the sharpness (I mean how agressively they negotiate for their staffs!) of the employer who gives the business to TIAA-CREF.
Don't think I'm putting you off, or saying you shouldn't complain. Now that some Institutional Mutual Fund customers (in the secret (!) Access program) get an even lower expense ratio than the "regular" Retirement class shares, I'm as steamed as you are. I feel they're screwing long-term, loyal customers like me. This last development is even a step below what you complained about. (That is, it's not precisely what you posted about.)
Until now, all variable annuity, 403(b) and IRA mutual fund, all RA or SRA or GSRA were treated the same within one group, if not the same in all groups.
I should add that variable annuities can be expected to cost slightly more than regular mutual funds, but not as much as the CREF VAs do today. For 20 years, the CREF Stock Fund only cost 0.22% to 0.24%.
Tim