I remember similar questions, "Why do you need more than 1GB hard drive?", "Why do you need more than 8MB of RAM?" Because it lays the foundation for new and better services and products. I imagine that Apple and others are laying down the foundation for tools and services like mobile AR/VR. Imagine the bandwidth requirements when everyone is wearing Apple Glasses streaming and receiving video feeds with AR 3D models and geographic data, constantly. 5G or 5G+ may not even be enough 10 years from now. This is just like more storage space, more memory, faster GPUs and CPUs from my perspective. We need it to do and create more new things we couldn't do yesterday.
I get 1Gbps/1Gbps and wish I had more. I think ultimately hardware, bandwidth, and latency won't be our problem with technology and advancements, but more the cost, and sadly, wealth disparity. The technology, the tools, the services, and the bandwidth to support them are coming, but it will likely become increasingly unaffordable for many. Imagine the next generation of educational technology, attending a full VR classroom, or instant access to the best AI tools to help you succeed at any endeavour. These could be available to anyone, any parent, any student, any business venture, but they probably won't be. And, only some people will gain extreme, ever-increasing competitive advantages.