The relative frequency of the letter B is only 1.5%[1] so it doesn't really matter.

[1] https://en.wikipedia.org/wiki/Letter_frequency

Edit: Assuming English of course. But a cursory glance of other languages shows that the frequency is not much better, if at all. French 'B' has a frequency of only 0.9%; Finnish is the lowest at 0.2% and Turkish the highest at 2.8% - but still, relatively low. So why bother optimising for a letter you rarely use?