My Understanding:
Initially, music stations pulled their streams because ASCAP, BMI & SESAC wanted the stream to be recognized as a separate means of transmission, and therefore wanted separate royalties to be paid. So every time "I Wanna Rock & Roll All Night" aired and went out over the stream, said station was to pay 2x the royalties. The law/rule as defined now actually recognizes the fees paid as including the stream:
"In the on-line radio world, the fees due to the composers of music through ASCAP, BMI and SESAC continue to be paid, in a manner much like the fees have been paid in the terrestrial radio world. For an internet-only station, the fees involve a flat fee plus a percentage of revenue once revenues have reached a certain level. For internet radio stations that simulcast the signal of an over-the-air station on a nonsubscriptionbasis, fees are basically included in the new ASCAP and BMI broadcast licenses."
Therefore, stations now that are holding commercials back from their stream, are likely gearing up, or in the process of, charging and/or finding ways to charge for the "air time" and exposure over the net.