I think the issue is the salary cap, not the roster size. It wouldn't help to expand rosters unless you bump the salary cap. Now maybe you add two roster spots and bump the salary cap by two minimum salaries -- that would make sense.
To cut costs, you could limit traveling party to 12, so if you have a 14-player roster and everyone's healthy, only 12 can suit up.
But I think you have to renegotiate the CBA to make that happen ...