Currently, Set-DRSClusterGroup does not appear to allow setting the name/label of a DRS VM/Host Group. Something like the following should work to modify the group name:
$currentGroupObj = Get-DRSClusterGroup -Name "MyCurrentGroupName"
$updatedGroupObj = $currentGroupObj | Set-DRSClusterGroup -Name "MyNewGroupName" -Confirm:$false
I would consider this a higher need since I am not aware of ANY facility to rename a DRS VM/Host Group name.
This no longer works in PowerCLI 13.2.1 since the Name parameter has been dropped:
SYNTAX
Set-DrsClusterGroup [-DrsClusterGroup] <DrsClusterGroup> [-VM] <VirtualMachine[]> [-Add] [-Remove] [-RunAsync] [-Server <VIServer[]>] [-Confirm] [-WhatIf] [<CommonParameters>]
Set-DrsClusterGroup [-DrsClusterGroup] <DrsClusterGroup> [-VMHost] <VMHost[]> [-Add] [-Remove] [-RunAsync] [-Server <VIServer[]>] [-Confirm] [-WhatIf] [<CommonParameters>]
definetly still a requirement - everything should be possible to rename