This is not exactly correct. They will be offering tubs in some levels. From Oceania recently:
Based on feedback from guests, one of the major upgrades to the accommodations is that bathrooms in all category C Oceanview Staterooms, all category B1, B2, and B3 Veranda Staterooms, all category A1, A2, and A3 Concierge Level Veranda Staterooms, and all category PH1 and PH2 Penthouse Suites will now feature an oversized, walk-in shower. The dramatically more spacious and functional walk-in shower was made possible by removing the under-utilized separate bathtub and small shower stall.