Yes, most domestic US airlines have eliminated change fees. But as you point out, it's not possible to get your money back and it's not easy to make changes if you don't have an alternative trip in mind. Cancellability is valuable (see hotel bookings), and yet, people over-value the option - sometimes out of laziness, or they forgot, or they go with the original plan. I have difficulty believing airlines would lose very much if they offered full refundability up to about 3 or 4 months in advance, but they would probably get more bookings, most of which would likely not get cancelled.
A lot depends on your travel habits. Credit on my usual airline (United) is pretty much a no-brainer within the year--I'll use it barring circumstances where losing some airline dollars are the least of my problems. Less so than it used to be but still.
For hotels, I still tend to pay the premium. I don't expect to cancel but, especially for an extended city stay, it can be a fair amount of money and the premium usually isn't that huge.