In a word?
Security.
Sure a vm is a little more administration to setup and manage (really quite a tiny amount in fact) but what you get is a resource that you have ultimate control over.
You can turn it off whenever you like and you can manage the SSL certificates and the firewall rules (see the admin isn’t so bad)
Not so with SAAS.
Sure it may be less admin but the big question mark is security.
And no matter what the SAAS company tells you, there will always be a question mark over this. Especially when they’re updating their software.
So the question is, how do you feel about a SAAS company’s software accessing your cloud resources?
We’re talking about your data in storage as well as your data warehouse!
Scary thought.