Right now, you can't see how many licenses are purchased in the tenant. And no, it is not the same as assigned + available. Assigned can be over subscribed. You are unable to determine this from the Azure AD -> Licenses -> Products blade.

Be able to show the "ActiveUnits" value for each license in the tenant. Same as the output from Get-MsolAccountSku.

Better yet, add the standard column picker to the grid view on this blade.