One reason consultants are hired
They usually buy the lunch and pay for the drinks.
For companies accustomed to picking up the tab for customers, this is a refreshing change. :)
Also, having the wherewithall to afford consultants is a sign that you have arrived as a company.
I worked for a company that we grew from small to very large and we went from a posture where we would have laughed at the idea of hiring consultants to hiring them at the drop of a hat.