What is benefit of braces if only two teeth are slightly off?

Depends: If two teeth are just slightly off and it is not a cosmetic problem for you...Spend your money on something else! if it bothers you an orthodontist can quickly align a few teeth if all else is normal.

How do you feel?: Depends upon how you feel about those two teeth. As years go by, we see teeth adjust and become more crowded, especially the lower front teeth. Two crooked teeth turn into three, then four.....Seek a professional opinion and follow their recommendation. You may need minor treatment only to prevent further crowding later.

Depends: You don't have to get braces, that is totally your decision. If the orthodontist told you that you need braces, your case is probably more complex than just moving those two teeth. Sometimes a very simple tooth movement case can be more complicated by the way your teeth bite together (occlusion). Invisalign may also be a treatment option for you.

Simple or more to it: Was your occlusion (bite) evaluated by a dentist or is this situation your observation? If your teeth and gums are healthy and you are not concerned about the esthetics, than it's a personal preference whether or not to seek the "ideal". However, what appears to you as a slight discrepancy, might be more involved both to correct and important long term. What does your dentist advise?