Needless to say that ecologists see the 5G deployment as utter madness, especially since, in their view, 4G is good enough.
More and more of the use cases move away from providing higher data rates to smartphones, so yes, oone could argue that 4G is currently good enough for that specific use case, but that's just one among many.
5G is about supporting greater capacity in general (so maybe the same rate as 4G but to more users at the same time, which is important in dense areas), massive IOT, extremely short latency, high reliability. These are important use cases but they are mostly off the radar of the average person.
It's impossible to see all the future exploits the new technology allows. All the things we do are built upon other existing ideas, moving to higher speed, lower latency connection is another step in progress.
Think about being able to download several GiB application on the fly just to view a demo for a house, or get the schematics for what you're viewing in realtime with AR
I would bet that 5G has cut down base stations which operate similarly to 4G, but the option to not use a new generation only works for maybe 1 generation before it gets too far behind. Data consumption is still going up after all, and some countries (such as Australia) have already mandated the shutdown of older generations, with 2G switched off to refarm spectrum, and 3G scheduled for switch off.