that's an aside. the point is: they told him to check-in. their system is flawed. they took the time to hire someone to program the ability to cancel the whole flight, but they ignored the part where they tell him to check-in. to make things worse, they treated him terribly when he tried to and didn't realize his "mistake."
Terms of Carriage/Fare Rules are actually quite important. I absolutely do check things like change fees, reroutability, fare class, etc. when I buy a ticket, and will often pay the 5% premium to get a more changeable ticket.
This is much more like reading the tech specs for a new laptop (does it have a linux-supported wifi chipset? discrete graphics?) than a EULA.
A useful fact you may not know: most "legacy" carriers will interline you onto another airline if they can't accommodate your scheduled travel -- for instance, if they cancel a flight, they will put you on another airline's flight if it will get your there faster. This is a VERY BIG DEAL internationally, where they don't always even have daily flights -- if a flight is canceled, it could be 2-3 days before the next flight with the same airline to your destination. Low cost carriers (e.g. Southwest) won't.
I've flown on some airlines where they send mail encouraging online checkin which also includes "miss your flight" information. And, I've flown others where if you miss you flight, they call or email or SMS you and try to work with you on rebooking to a later flight (either standby for free or a small fee, or rebooking for $50-150), plus any difference in fare. This would still support price discrimination and market segmentation.
The vast majority of people who miss their outbound leg are still wanting travel on the outbound leg at a later time, not to burn the outbound leg and take the return leg. That is the failure mode to try to optimize, not the return leg.