Generally speaking, sex is always better going bare. There is that wonderful intimate feeling of two people deeply connected and touching each other in a special way which is normally reserved for hubby.
As a guy, there is a deep sense of satisfaction cumming deep in someone. This is the most intense and more intimate, leaving your seed and marking that space as yours. I can only guess that as a bull, to be able to take someone else's girl and repeated cum in them, whilst she is willing and fully accepting would be a massive ego boost and a huge turn on.
From what I have heard from my ex-gf, she loved having a man cum in her, made her feel more feminine. She enjoyed the feeling of wetness between her legs that lasted afterwards, knowing that she was carrying his cum. For her, she felt that male orgasm and his cum was her reward for a job well done.