Too many of the arguments I've read and heard for hiring more full-time faculty rely on moralistic appeals. The idea seems to boil down to a simpleminded equation of "market" with "bad" and "tradition" with "good." Moralistic arguments don't work because they solve the wrong problem. But there's a perfectly reasonable market-based argument for hiring full-time faculty right now: buy low, sell high. Great people have never been as undervalued as they are now; this is an unprecedented hiring opportunity.