VNXe has lot more extra components than VNX while storage provisioning. It also has some best practice algorithms inbuilt to make storage creation lot easier for end users (IT generalists). I'm not sure if you have used the latest OE release 2.4.0 which is faster than its predecessors. If you have not tried, I recommend to upgrade.
This might be a stupid question, but why is the LUN creation time on a VNXe take so log compared to a VNX.  I realize they are two different platforms, but it just seems like depending on size and type of disk, it can take forever
LUN creation time