I do some consulting on the side and I won't charge by the hour if I can avoid it because:
1) I hate keeping track of time.
2) hourly rates aren't how my customers think of the issue. They think: "this product will make (or save) me $20,000/year" (making up numbers here). If I tell them that I can do the job for $5,000, that sounds like a great deal to them. But if I tell them I can do it for $200/hour, and I estimate it will take me 20/hours, then I just look like an expensive consultant. Notice that in the first scenario, I made more money and still seem cheaper.
1) I hate keeping track of time.
2) hourly rates aren't how my customers think of the issue. They think: "this product will make (or save) me $20,000/year" (making up numbers here). If I tell them that I can do the job for $5,000, that sounds like a great deal to them. But if I tell them I can do it for $200/hour, and I estimate it will take me 20/hours, then I just look like an expensive consultant. Notice that in the first scenario, I made more money and still seem cheaper.