Offering someone a job should not be anti-climatic. In the eyes of the prospective employee it is the most important part of the process, and it should be dealt with care and attention. My job at this point in the process is to make sure there are no surprises. And that holds true for both the hiring company and the prospective employee. If the offer is not realistic for both parties, then I haven’t done my job.
As a general rule, I like to see the offer made over the phone, if in person is not practical, and followed up in written form shortly thereafter. I’m often asked to make the offer, and as a matter of course, I prefer not to. My experience is that if there are glitches in the offer, a middleman is in the way. Direct communication between the company and the prospective employee is best at this point.