Players should fight fewer Rare Monsters at once, but they should be more challenging and rewarding.
In fights with a lot of Rare monsters on screen, you can’t follow what modifiers they have, what skills they’re using, and sometimes not even what type of monster they are. There’s too much to pay attention to, with too much noise and screen pollution. You cannot use appropriate combat tactics, and instead have to just stutter step or be so powerful that it’s inconsequential.
Fewer, more difficult rare monsters help you pay attention to what is happening, assess it, and act accordingly. It gives you an opportunity to employ counterplay and for your playskill to actually matter (rather than relying on pure character power). It is also a lot cleaner and far better for performance.
Rewards should be set appropriately for the increased difficulty of these rare monsters.