I hate the idea of baths in bedrooms, especially because of the steam and moisture, it would need very good ventilation / dehumidifying to avoid damp and mould.
However bedroom 2 looks large enough that could easily put walls around it and turn it into a normal ensuite ... maybe they ran out of money or giving the next owners an "option"? 
I love the long windows and how they've tried to make the best of a fairly narrow plot though - I'd probably buy it if I had the cash and a bit spare to sort out bedroom 2 