The announcement says that they're eliminating bandwidth charges three times.
I don't know the whole economics around cloud storage and bandwidth so maybe this is unrealistic pricing and your suspicions are well founded. However, Backblaze seems is offering storage at $0.005/GB and bandwidth at $0.01/GB. Cloudflare is charging 3x more than Backblaze for the storage and $0 for the bandwidth. Given that Cloudflare's costs are probably lower than Backblaze for bandwidth, that doesn't seem so unreasonable - but I could be very wrong.
I think Cloudflare probably sees R2 as something that is sustainable, but creates demand for their enterprise products. You start The NextBigThing with R2 and suddenly your application servers are under attack. You have a relationship with Cloudflare, you're used to their control panel, you trust them, and when you're at the scale that you're getting attacked like this you can drop $10,000/mo because you're bringing in a bunch of revenue - $10,000/mo is less than 1 software engineer in the US.
R2, in a certain way, can be a marketing tool. "Come use our S3 competitor with free bandwidth rather than getting locked into AWS's transfer pricing." 6-12 months go by and you're substantially larger and want more complex stuff and you're already getting emails from Cloudflare about their other offerings, you see them in the control panel, etc.
It seems like Cloudflare might be trying to move in on AWS's market. R2 is an easy way for them to do it. It seems like S3 has high margins. Competing storage services can be a fraction of the cost per GB and AWS's bandwidth markup is incredibly high. If you're looking to attack a competitor's market, it seems like going after one of their highest-margin product could make the most sense. Again, R2 becomes a marketing tool for future cloud offerings.
Part of Cloudflare's strategy might be targeting things that they see very high margins on and being willing to accept lower margins. If something has 50% margins and you're willing to accept 20% margins, you're still doing pretty great. Plus, over time, the cost of hardware comes down and you can keep your prices at the same level once people are happily inside your ecosystem and don't want to deal with migrations.
> CloudFlare bandwidth is some of the most expensive available
It sounds like you might have gotten burned by something with Cloudflare. I don't have any horror stories, but I'm always interested in new data points if you have them.