Hmm, well first off, I'll preface this by using the canon example. Yes, those of large stature have CVR-3 available to them. Case in point; Lunk! Guy is huge! And, we did see him in CVR-3 in the final episodes of the 'Invid Invasion'. Now, we can follow two examples, one real world, the other, not so much. The 'not so much' I will tackle first. Take your run of the mill Stormtrooper outfit from SW.
By this pic (Nerds Ahoy!) We can see that a standard suit of armor is made in numerous sizes. (Evidenced by the difference in the lower chest pieces. Note how the upper plate overlaps the lower by varying degrees based on the height of the wearer) … And wow, mister Officer costume wearer, stop being a mouth breather! Can you at least TRY to look Imperious?
The Main protective plate, the chest plate, remains the same regardless of the size.
The real world example is more or less can be seen here
While the armor comes in different sizes, the protection value is the same. Yes the person may be carrying more armor in terms of aggregate weight, but, that is what is needed to cover that persons body.
I see your points, but in order to keep the game simple, in so much as we aren't getting bogged down by different values of armor for each individual person, (because, by the same argument that confers +5 MD to some one who is large, the counter argument of -5 to one who is small (Sarah, Anji, Suki) can be made.) a standardized value should be just that, standard.
As for the use of CVR-3M by a female. That is up to the player. Case in point, Ishida Suki figured that it would be better to have some added protection, and thus elected to use CVR-3M within the mountain rather then CVR-3F (and would prefer the CVR-3F within her Alpha (or VR-059) because it is more comfortable.) If a male character wants to use CVR-3F, they can, if they wish, and vise-versa. (Note: I declared that prior to session kick off as a subtle hint to everyone that yes you can use whatever armor class you wish, and that no, gender does NOT pigeon hole you into a certain armor type.) Also take into consideration that a male may WANT to use CVR-3F when stealth is necessary as the M version confers a -10% to Acrobatics, Climbing, Gymnastics, and Prowl, while the CVR-3F only has a -5%.
This is the frame of mind I am coming from.