- Bandwidth is VERY expensive in AWS compared to what you can buy in Datacenters. A 1 GBPS connection is so "cheap" you can get it and a 42U rack at HE.net for $400/mo ( http://he.net/colocation.html ). That same 1GBPS is roughly 300TB/month. Assuming it's all outbound - that's roughly $21k in AWS.
So bandwidth is a small cost IF you're not moving large amounts of data out of AWS. If you stream media - it can be a HUGE portion of your bill.
- HIPAA Compliance - That and other compliance aspects assumes that you need those compliance frameworks. In enterprise world that might be the case (SOC2 and ISO27k1 are very common requirements for Enterprise SaaS clients). However in the B2C? Users don't care.
- Waiting for hardware allocation. Once you get to a certain size you have hardware spare, typically. Developers can use that for their tests. You can also have your datacenter/operations group work with your developers during project planning so the code and HW can be ready at the same time.
That being said, I don't disagree there are advantages to the cloud. I'm AWS certified, I drink the coolaid. But saying that there are "so many other benefits" is ignoring the fact that there are "so many benefits" to on prem too. There are pro's and cons to both sides.