Why do I bulk load? Because there is a cost saving with B&W film.
I'm currently running two bulk loaders, one with Fomapan 100 and one with Ilford HP5+
I tend to roll 36 exposure cassettes but it's nice to know I can make one with any length I wish. I can get 9 or 10 36 exposure films from a 50 foot (17 metre) roll. At £23 for the Fomapan and £36 for the HP5+ that is a saving or around 50% on over the counter prices and at least 1/3 on buying individual films online.
I also find it quite fun. It doesn't take long, nor does it take up much space. the cost savings please she who must be obeyed as she knows ceasing B&W photography is not negotiable. Any savings that I can make keep her happy, and allows me to buy more film

Additionally I tend to have about 6-8 cassettes available for use at any one time, as I am not someone who practices photography every day. The bulk loaders actually take up less space than having 20-40 rolls around.
I find with a Watson or similar, I lose 2-3 frames at the end of a roll. But the advantage is that machine seems really well made and solid as a rock, and has a frame counter. The Lloyds style ("The Daylight") I lose about 1/2 to one frame at the end, and the lack of a frame counter isn't really a problem if I am honest.
I am also an occasional bidder on auctions for outdated B&W film, and even more occasionally colour. Although I like to support the remaining manufacturers by buying new film, this can be a very cheap way to obtain more film.