Why do hotel bills need to be itemized for the IRS?

Hotel bills must be itemized because only a subset of expenses are tax-deductible. Your lodging, meals, and even items like dry cleaning are deductible. But expenses like using gym facilities, watching paid movies, or playing games are not.

Documentation 17 from IRS has a very complete set of information on this. http://www.irs.gov/pub/irs-pdf/p17.pdf