Future ready, today.
We ran out of IPv4 space by the end of 2019. While you can acquire IPv4 space on the market, it is very expensive and effectively limiting new projects to come into existence. IPv6 fixes all of this, today.
Compared to IPv4 only or Dual Stack VMs, IPv6 only VMs are the only ones really ready for the future. IPv4 only VMs already face the problem that they cannot reach resources in the IPv6 Internet. Dual stack VMs are increasing complexity and difficulty, especially when it comes to firewall rules and security.
IPv6 only hosting is giving you access to virtual machines that will become the standard tomorrow, already today. Instead of managing legacy IP VMs with NAT, creating floating IP addresses and complex firewall setups, all this burden is lifted away with IPv6 only VMs.
Additionally you can request a /64 network to be routed to your VM, for free!