Well I found a solution!
You know how there are level sets with a bunch of rotating maps (e.g. Dark City, Scarlet Fortress, etc.)? Well I think that certain floors of boss stratums should have multiple versions, say, Ashen Armory I-II, or Abandoned Assembly I-III. it would add more variety to a boss level and you would have more fun. You wouldn't be like, Oh, we're up to this same boring floor that I've done a million times and know the exact amount of enemies in it. Multiple floors would mix things up a bit and make it more fun. :D
Eventually, you'll get used to all 3 variations too.
But my real complain is... if you get bored of boss runs, well, stop doing them!
If people get bored and quit, it's because they want to and don't realize no one is forcing them to do FSC over and over.
The arcade is always random.