A B foot is rarely needed. In 40+ years, I've seen less than 10 pieces of music with a low B.
It really does not affect the response of the flute, so on that front it really is a "don't care" consideration. The only downside is that some players don't like the extra weight that it adds to the end of the flute and feel it affects the balance when holding/playing. Me, I'm a doubler and the weight is negligible. I don't notice any significant difference - with or without the B.
It really depends how much you want to spend. Lower end flutes often come with a C foot while intermediate and pro flutes usually have the B foot.
"Never give a flute player a screwdriver."