Likely, nobody including the devs have tested 200 separate cache instances versus a cache with 200 regions.
Given that there are limitations on what you can do within a region, specifically you can't configure a per-region cache loader yet, you would need separate cache instances.
I can't see anything wrong with 200 cache instances, just potential headaches with dealing with configuration. You do lose a bit of efficiency, in terms of memory.
What might be a good compromise would be to create about 10 different "flavors" of caches and share these amongst the 200 applications.
What you could also do is multiplex over a single JGroups channel. This way 200 caches share a single network socket for comms.
Although I doubt the JGroups multiplexer has been stressed with 200 caches! ;)