You are allowed to depreciate the value of a building over 27.5 years, or, for more sophisticated investors over 5, 7, and 15-year periods. The depreciation expense is recorded on your statement of cashflows, similar to a normal expense, and it reduces income, which means you pay no taxes on the depreciated dollars.
"Other reasons" is meant to be general enough to include all reasons people do things which you and I might not see fit to do, there are infinitely many of them.
The larger your portfolio, the more you benefit from tax advantaged plays, which the normal cashflow investor doesn't think about.