Sparky,
I agree with you if i could have a buck everytime someone wanted a 200 amp service could retire.
the First question is why do you think you need one, and 99 % of the time is, " Well Iam going to be putting a welder in the garage" I have gotten to the point that I ask now, 200 amp hmmm, do you think that will be big enough, we can go to 400 amp if you feel safer this is all tongue in cheek, but it makes the point.
Generally we do three types of resi services 100, 150 and 200 amp services. like Tom says the customer is always right, but I try not to sell them something they dont need either.