Parks Associates reported last year that 60% of respondents in a survey valued a rewards program for being a loyal customers, third only to the ability to roll over unused data (66%) and free access to Wi-Fi hotspots (65%) as “very important” when considering a new service provider.

"The U.S. mobile service market has grown intensely competitive over the last three years as growth in new smartphone subscribers tapers off," Harry Wang, Parks' senior director of research, said last year. "U.S. operators have ramped up incentives to lure subscribers from competitors and encourage their own to stay longer—their game plans have switched gears from ARPU growth to churn management. The migration away from a two-year contract has made service switching easier for consumers, and consequently mobile service providers are facing more pressure on churn."

From the article "AT&T kills Plenti loyalty program but touts ongoing Thanks campaign" by Colin Gibbs.