I semi agree that I dont think we know what this is for. Never ever having buffer bloat is a tempting first ask. Connectivity is more than the sum of throughputs, as your figures imply- there's questions of availability too.
Being able to access each other's systems at near local speeds sounds quite compelling, could help jumpstart post-Big Social computing. You talk about netflix streams, but those are heavily compressed with the best offline encoding on the planet: if i just want to open Steam Remote Play Together & share realtime 4K with a friend, I'd need a lot more throughput since I have much much much less efficiemt encoding. If i wanted Remote Play Together with 3 friends, well, that figures goes up. If my family member also wants to do the same, now we're using a lot or maybe all the throughput & we're starting to have some contested bandwidth, some rising latencies.
The truth is somewhere between. Rationalizing ourselves down to what sounds sensible today, to me, is a cruel trick, is not just path dependency but an ideology that believes only in what we have & can see now, & refuses exploration & trying. To me the world & tech is spiritually fueled by why not thinking, by deciding to opt for the extra thats within reach.
Forgoing a cheap (still less than the price of a nice tv, by far), available one-time purchase option that vaults us into near-local connevtivity caliber with the world is still a lock in my book.
There's benefits to 25G (certainly when transporting 4K video around which needs more than a 10G nic), whether that's worthwhile for a typical home is likely "no", so unless you've got hundereds of employees in an office it doesn't feel very useful.
To actually realize your faster speeds, you need to spend thousands of dollars yourself on new switches and NICs. And then, as mentioned, the benefits are marginal. You would have to be streaming 10+ 4K movies at once to even "need" gigabit, let alone 25Gbps.