It really is for aesthetic purposes. I think traditonally cornicing and skirts were used to cover any flaws in the plaster where the walls met the ceiling/floors. It can also give a roundness to the room and avoid shadows where the wall and ceiling meet. On the flip side, if painted white it can give the appearance of a bigger ceiling ceiling and therefore shorter walls. Nowadays a lot of contemporary homes do not have coving. I think it depends on what you like, personally I love it in the right space. What do you mean by low beams btw?

I guess it depends, among other things, on the style and period of the house. What period was it built?

We’ve recently had a French style curtain pole made for our room, albeit straight rather than on a bay. But worth talking to someone about options. The main thing for us was not wanting any support in the middle, and we have achieved that. We went to Smithy Ironworks and have a lovely black pole which doesn’t come too far out from the window frame. There are other places that make poles for bay windows. Just a thought, would go nicely with your fireplace.

I think if its the only room with coving then you can safely remove it so that it all looks continuous. It might make the ceiling look slightly higher too as it would elongate the walls a bit. If your house was Georgian, Victorian or Edwardian I would give you the opposite advice. To play devils advocate it's always easier to paint the walls a different colour to the ceiling if you have coving to stop against.