It's not about whether a "new home", a new build as I understand it, needs a bathtub, it's about whether the type of home you are talking about needs it. You haven't included the description.

How long do you plan to be living there? Like Kate said, your house, your choice. But if you can see yourselves selling to upgrade or to move to another city or whatever reason, you probably should take into account what other people want in a house. Redecorating is one thing, but the prospect of major renovation involving plumbing is something else.

What sort of house is it? A 4-5 bedroom 'family home' type house I think does need the usual 'family home' type features for resale value. In a smaller house it's debateable, though it should be proportional, if some rooms are luxe while others are skimping, it's not proportional.

How small is the bedroom that you feel the need to make it bigger?

If you have plans showing with and without bath keep them to show future buyers how the could add a bath

So you've seen the replies. Did you find an answer applicable to your house or is anything in the debatable category, in which case providing a more useful description might help. Your original question appeared to be about whether a 'new' house needs a bathtub and as I tried to explain, the newness isn't the main question relevant to your decision.

A. If you don't need/want a bathtub + This is expected to be your forever home + You don't have children, will not have future children or grandchildren here. Ok, no bath.
B. Your home for a while, then sell it. Add bath.
C. Investment property. Add bath.