Big Law firms in the last few years have launched a flurry of new offices in smaller cities, from Nashville, Tennessee, to Austin, Texas, and Salt Lake City—areas where billing rates are far below those in New York, Washington, D.C., and Los Angeles.

But analysts say the value proposition for law firms, even for some of the most profitable firms that can’t command their usual rates in such cities, is simple: enticing talent, being near valuable clients, and adding offices with lower overhead costs.