I believe that is often the only reason to do it. For example my wife recently applied for and got non-profit status for our sons school PTO. It's a win-win since it encourages more donations while lowering the tax bill of those donating.
Yes, but that's not a great as many people think, and is actually a common misunderstanding about tax deductible items.
Example
Assume your taxable income after all deductions is $100,000, and you pay 25% tax, or $25,000
Donating $10,000 to charity reduces your taxable income to $90,000, and you now pay $22,500 tax
Ok great, but you've spent $10,000 to save $2,500 in tax.
But you feel good because at the end of the day you've only paid $7500 and the charity gets $10,000
Believe it or not a lot of people think that they get the whole $10,000 back