Well do "you" know what Band 30 is used for? 😵😵😵
AT&T is still rolling out Band 30 aka the WCS spectrum to only a few Metro areas even today. It will be part of the long-term network. Apple made it clear at the iPhone SE announcement: the iPhone SE will not support LTE Advanced (300 Mbps) only LTE at 150 Mbps.
Band 30 part of the overlay of it's national 700 MHz deployment, so you would expect to see urban areas benefit the most. Offloading traffic from the 700 MHz and also 2100 MHz AWS for LTE spectrum. Oh, and in some markets AT&T is also using carrier aggregation to combine 700 MHz and 2100 MHz.
Summary: Band 30 is a nice feature addition but not a world ender for 99.95% of AT&T customer. 😎
Note: LTE Advanced offers a range of benefits over standard LTE support in addition to higher theoretical throughput. For instance, LTE Advanced offers smoother "handoffs" when travelling between cell towers. This allows your smartphone to not drop the connection so much.
Dave