It impresses me as a user though since ETag still incurs a round trip while "forever" expiration doesn't. There's a night and day difference between ETags and no HTTP request at all.
You are likely complacent because you're always on a good connection, since you keep arguing in these comments (even farther down) as if conditional GET requests obsolete other forms of caching.
The real benefit of ETags is that they generalize over all content dynamically, but they come at the cost of incurring more requests than expiration caching. I don't see how you could keep arguing here unless you didn't understand that trade-off.