Allow multiple private networks to be defined (with private custom IP ranges). These VPCs (such as VPC-Traffic and VPC-Management) can then be allocated to different instances. Once these are allocated, users should be able to choose specific IP addresses for instances (either via DO or via netplan).
Such flexibility would allow for much better planning and management of IP traffic for Enterprise applications.
This capability is currently offered by at least one of your competitors (Vultr).