What you're describing for "unlimited" is what would be termed in a data center "unmetered". If I buy a 100 Mbit unmetered pipe, I can do exactly as you say, max out the 100 Mbit pipe 24x7 as I please.
What customers really want, most likely, is something like a "burstable" connection with reasonable limits. Let's say I buy a 100 Mbit "burstable" connection with a 10 Mbit commit. That means I can use up to 100 Mbits at any moment, but if the average is over 10 Mbit I pay more. (It's actually not average, it's 95th percentile, but we'll call it "average" for this conversation)
So there are limits! Fine. I'd happily go for an agreement that
1) states an average data rate,
2) Allows me to burst up to 4x or 5x that rate,
3) Throttles later in the month to maintain the average data rate or less.
4) As technology advances so that bits are cheaper/faster to send my average data rate climbs, or monthly price drops
I think the problem isn't with 1, 2, or 3, but with #4 It's much cheaper to send a GB of data now than it was 3-5 years ago. Why hasn't my usage cap gone up, or my monthly price dropped? Until that question is answered, all we're dealing with are lies and spin.