Because provisioning is slow, especially for additional IPv4 networks. They could provide a PaaS-Services like e.g. https://stackdock.com/ utilizing Docker. Or at least some virtual private-networking and iSCSI-block storage and object storage (like S3).

Honestly their cheap-server-design could be a great foundation for something, if they federate it and provide it. It's nearly unmanagble to do it yourself as you don't have a privat interconnect, availability/redundancy (e.g. in which DC the put a system) and you can only have one failover IP/network per system.

Also they have really bad luck with hard drives. I've had SMART errors/disk replacement in 3 or 4 disks on a single machine over the past 2 years.