Never heard of a plane being made strictly for weekly scenarios.
No plane is ever made JUST for the scenarios and FSO. And guaranteed on virtue of sheer firepower alone the P-61 will see usage on the Mains. The B-25H on paper is a hangar queen. She's slow, has poor rate of climb and altitude performance, not very maneuverable, only about average in defensive fire coverage, near the bottom of the multi-engine bomber pile when it comes to ordinance loadout. If you look at the balance of her stats, this is a plane that would gain very little use in the Mains and would seem relegated to scenario play.
And yet the B-25H has developed a VERY loyal following and sees a healthy amount of usage. Why? Because she packs one MASSIVE gun. The 75mm makes the B-25H one of the premier close air support aircraft in the game, second to only the 37mm on the Il-2. She can de-ack a field without subjecting herself to return fire--and if you're REALLY good with it you can do the same with Wirbleweasle turrets--and single-ping tanks if you know where to aim.
The P-61 may not have that much firepower, but you still have a LETHAL cone of fire from the 4 20mm and 4 .50cal. This would make her a strafer at LEAST on par with the 110G-2 for town busting, if not outright superior. Certainly, the G-2 will only surpass that strafing capability with the 4x20mm and 2x30mm package, but she sacrifices much of her ordinance to do so (with the full gun package she can only carry 400lbs of ordinance. Taking the two 1000lb bombs eliminates one pair of 20mm). The P-61 carries nearly TRIPLE that, without sacrificing her gun package. Then of course factor in that these are HISPANOS.