Good support is invaluable.
As others mentioned already there's many situations where you'll find you need 'support' in some capacity.
Server support
Fair enough if you know what your doing. But in the case where you need a little helping hand? Nothing beats literally getting on the phone and asking some tech guy on the other side about it. Someone who could hand to hand guide to you in some cases. Even the most experienced would like someone to bat ideas and troubleshooting with when things go wrong.
Unmanaged and Managed servers
This service offering isn't consistent across the industry. One providers idea of managed is another's standard unmanaged service. And some places doesn't provider any support full stop.
account support
Aside from server side things. For as long as you part money with a company, you want to be able to easily get in touch. Pay bills, cancel service, upgrade service, ask for advice on a server hitting it's limits. Whatever it is, you're bound to want to have some kind of support from them. I guarantee you, nothing puts people off more than not being able to find a straight answer for anything. Or it takes 1 week for anyone to get back to you, to which by then, your business has taken a serious hit.
If your server is critical to you for whatever you use it for, you best hope someone answers the phone on the other side.
We find that businesses value support more than price. But of course, if the price is competitive.. then its all win win.