Every electronic device's power is managed or as you like to call it "throttled". This is nothing new. These "throttling" cases will be thrown out because it would create a precarious precedent. Every device has what's called a user or licensing agreement. It'd be hard to argue that throttling is interfering with your enjoyment (which resulted in you to buying a new device) because you agreed that it wouldn't in the license agreement of iOS. In fact, a judge would ask "If you didn't enjoy this device, why did you buy another one?"
7.4 APPLE DOES NOT WARRANT AGAINST INTERFERENCE WITH YOUR ENJOYMENT OF THE iOS SOFTWARE AND SERVICES, THAT THE FUNCTIONS CONTAINED IN, OR SERVICES PERFORMED OR PROVIDED BY, THE iOS SOFTWARE WILL MEET YOUR REQUIREMENTS, THAT THE OPERATION OF THE iOS SOFTWARE AND SERVICES WILL BE UNINTERRUPTED OR ERROR-FREE, THAT ANY SERVICE WILL CONTINUE TO BE MADE AVAILABLE, THAT DEFECTS IN THE iOS SOFTWARE OR SERVICES WILL BE CORRECTED, OR THAT THE iOS SOFTWARE WILL BE COMPATIBLE OR WORK WITH ANY THIRD PARTY SOFTWARE, APPLICATIONS OR THIRD PARTY SERVICES. INSTALLATION OF THIS iOS SOFTWARE MAY AFFECT THE AVAILABILITY AND USABILITY OF THIRD PARTY SOFTWARE, APPLICATIONS OR THIRD PARTY SERVICES, AS WELL AS APPLE PRODUCTS AND SERVICES.
[Source:
http://images.apple.com/legal/sla/docs/iOS112.pdf]
If you can sue Apple for iOS power management, then you'd be also able to sue Apple for notifications that distract you while driving and result in an accident. But you can't because you agreed to the license agreement.