Of course two 20mms in the wings would give it a better chance of defending itself. If you manage to get a snapshot at your attacker with those two BBs they do not have any effect, but with two 20mm MG151/20s it would be a very different matter. It also has a historical basis.
And 37mms? Well we also have a thing called
scenarios and there are big gunned AtoG planes available for allied side and none for axis. That alone supports the addition of 37mms for Ju87. Eg. imagine an east front scenario with 37mm Il-2s and Ju87s with BBs, OR a rule that prevents Il-2s from using 37mm because axis does not have it, veeeeery nice....
And if I may add still not even the single MGFF for Ju88A4, but of course there was also Ju88P which had various interesting gun options. Maybe we could have that?
Do I envy the various gun configurations for B25, hell yes. Is it any less a target for fighters due to its incredible gun load? Probably not, but it sure adds a lot to its appeal.
-C+