Poll: Sugar in spaghetti sauce? Yes or no?

It's been a while since I posted. I have a burning question that must be answered. Preferably right now. 

Why does nearly every spaghetti sauce I see have sugar in it? Is it really necessary? 

Here are some of the answers I ran across doing a brief Internet search:

• To tone down the acidity. 
• Just because we've always done it that way. 
• I prefer to use carrots; it's an Italian thing.
• I don't care why; it's wrong. 
• Isn't that illegal in some states? 

My guess is that it depends on how acidic the tomatoes used are. What do you think? It's relevant right now; I am planning to make homemade pasta sauce for dinner. 

Please answer quickly: should I put sugar in my spaghetti sauce or not? Why? 

Thanks for your input!