I kind of disagree. With signup bonuses and a variety of creative ways to maximize points, flying business vs. coach is like a man deciding to eat once at Cheesecake Factory rather than twice at McDonalds.
Business class is usually about 2/3 more than coach. If you can sign up for a bunch of credit cards, you can perhaps get 300,000 miles or points, which is 3 business-class trips to Europe or 5 coach trips. Admittedly it's not all THAT trivial. (For example, you can get 40K USAir points for signing up, but with limited transfer partners and them allowing only round-trip awards, it's not trivial to get your US account to 100K for a business class award.)
A purely personal perspective; as I get older I find myself achier and crankier and less willing to sit in coach on a long trip. I took my first-ever overseas trip last month and did fly business class both ways. I'm really happy I did, and unless I had a particular reason to be in Europe, I think I'd rather stay home and save my points for another trip than fly coach. If I had to pay the cash prices, where business class is 2-4 times as much as coach, it would be a different matter.
I might - might - feel differently if points were that hard to get, but by signing up for credit cards and using assorted tricks outlined on this website, my wife and I will earn about 800K points this year while flying almost not at all and spending only about $25K on credit cards. I certainly don't expect to do 800K every year, but it will be a nice stash to last us a few years.