It is my understanding that this airframe is already very weight-limited, and adding armaments is not a good idea, as it negates its' original raisin d'etre, which is transporting troops.
I am not sure if the issue is weight or space limitations, or both.
If it carries 24 Marines (plus three crew, maybe another crew if someone has to operate weapons) and you allow for 350 lbs for each passenger (with all gear), that comes out to a weight limit of 9800 lbs. The internal payload is around 20,000 lbs according to some sources (that is one number I saw for a hoist lift load, so it has to a vertical takeoff) so I would guess the 24 troop limit is due to space considerations and not weight, so adding external hardware such as the ordinance pods and such might not prevent them from carrying their troop loads, but would likely cut down on the range and speed, not to mention the vertical takeoff and land, but that isn’t a given.
This is only a guess.
From reading, it seems this is something they felt that they had to explore since the Osprey can outrange and outrun the traditional attack helicopters that would provide that type of armament support.
They want firepower available to be directed at where they’re going to be ingressing the troops...as the article states, they outrun conventional helo gunships.
I suspect that much will have to be done for this mod to be effective, especially considering the potential impact to range based on the pods being installed externally on the outer mold line. Drag coefficients and all.