1. Legacy IT consulting is rarely necessary
The cloud is remote, your datacenter is remotely accessible, the same consultants, so why? How else can they keep charging you those massive rates?
2. "Over The Shoulder" syndrome
We all like to look someone in the eyes before we turn over the keys. Is it really worth an extra $50-$100/hour? That's what webcams and electronic signatures are for.
3. Legacy consulting firms mostly want generalists
It's hard to keep utilization high while keeping as few consultants "on the bench" as possible. That means you're getting a resource that was just as likely working on a product with zero cross-over knowledge for the last 6 months or year. You want a hot knife through butter, not someone you're paying to learn.
4. Project delays mean more cost
Your IT project is delayed by the network guys, a missing hardware shipment, or a meteor strike. Think your on-site consulting firm will stop billing you?
5. Travel takes its toll
75,000 flights have been canceled for winter 2013, impacting an estimated 15,000,000 passengers. Those brave, but weary roadwarriors working on laptops and sleeping on flights will rarely measure up against that very same architect working from their command center in the cloud.
