What some in this thread are overlooking, in various degrees, are bike trail users. There are now hundreds of bike trails built in the USA. There are now thousands of miles of trails built. Many of these trails are very popular and have become tourist attractions. A lot of trail users do ride 20, 30, 40 and more miles.

These cyclists are out there riding a lot. They are buying millions of bicycles. Biking is an important part of their lives. And few of them are riding drop bar road bikes.

Another genre of regular bicycle rider is the commuter. Most of them do not ride long distances, but many ride 5, 7, 10 or more miles each way to work or school. They ride frequently, sometimes 200 days out of the year. Most of these people aren't buying drop bar bikes either.

Again, I'm not being critical of drop bar road bikes. They are beautiful machines that are the perfect solution to millions of people's needs. But they are not a predominant form factor for American bicycle users, even those who use their bikes a lot. And I suspect they are even less prevalent in many other countries.

It might seem like they are predominant to someone who takes long rides on roads. That is where these bikes live. But at the same time you are out there surrounded by drop bar bikes, there are millions riding other bikes in other places.

I'll add that I find riding on a perfectly flat bar that is attached via a long angle stem and without bar ends, can get darn uncomfortable.

And I encourage the OP to take the advice being given here by seasoned drop bar riders. It isn't surprising that you had some problems after making such a radical change on a long ride. When I took my first longer ride on a recumbent, the ride was very comfortable ... for a while. Then those different muscles in my legs that a 'bent exercises, started to kill me.