Boy, the BB hate is strong here.
One should take into account the ability of the BB to take a hit and get repaired when considering the purchase. Your opponent will have to when considering whether to attack it.
It’s not an insignificant ability - every time a BB eats a hit and gets repaired, it’s getting the value equivalent of a free sub (the cheapest unit one could lose in a naval battle). Plus of course that amphibious shot makes recapture of islands from Japan cheaper as well.
If you use a BB right, you can use it to greater effect than you can a DD and two subs and end up income-positive relative to the latter purchase.
Building in 101 as an alternative also has the drawback of being a turn behind in the Pac theater. This gives Japan more freedom of action as it will have to devote less to defending SZ6 against early raids.
If people were arguing for a CV purchase as an alternative to the BB I could agree with that. Not so much on the DD/subs, which could be purchased by ANZAC to the same effect anyway while the same is not true of a BB purchase.