They make up for the lack of intelligence by hiding the true quantity and composition of the mobs. When you trigger an encounter, there's a good chance that at least 10 more enemies will come flooding out of the side of the stage in a style reminiscent of other Japanese media depicting demon ambushes.
More is generally better - the meat of your exp gains will be from chaining as many kills as you can, which leads to times where you will purposely get the attention of many enemies at once to rack up the carnage. This may be harder on those who are not good at mitigating damage.
Unfortunately, this design choice runs counter to the lag issue.
