There are two key advantages to using VVol datastores versus traditional datastores:
Granular management approach for SAN storage
Support policy-based provisioning and management, which might be automated
For example, the granular management means you can monitor individual performance and capacity of VVol VMs using ONTAP data (for now, we display the data for the top 5 VMs in the VSC/VASA Provider dashboard). You can also set Max QoS at the VVol VM level, using Storage Capability Profiles.
Policy-based management allows you to define storage policies for your VMs to speed provisioning and avoid mistakes. This is useful if you have different classes of storage, perhaps SSD and SATA for production and test VMs.
It really depends on whether you want the additional benefits I described of SAN granular management (QoS and some performance monitoring) and policy-based management. If not, using traditional datastores may be simpler for you. Also, backup tools generally support VVol backup and restore using VADP, and aren't currently taking advantage of ONTAP snapshots. Finally, DR replication of VVols is not supported with VMware SRM.