As much as I would have loved it, I think Atlus stated that they weren't able to make P3P like the PS2 version because they weren't able to do the cutscenes with the character models. So they made up for it with a FemMC since it was easy to just put in new cutscenes because they were just pictures and text.
In the case of P4G, Atlus didn't want to undertake such a serious addition of a FemMC because that would mean having to recreate and animate new cutscenes with new models for S.Links. So instead they added lots of other extras such as S. Links, the extra month with events, and the TV Listings.
P4G would have been twice the size and way more work if they added in the FemMC.
Actually the reason they didn't do it is because while P3's initial concept had male and female options for the MC, P4 was built solely with a male character in mind.
If you can track down the earliest footage of Persona 3, it actually shows both the male and female main characters fighting a trio of cupids. Also interesting is it used the location the battle initiated as the battlefield, ala Breath of Fire 3. I watched it on the Atlus blog YEARS ago so it may not still be around.
Obviously the female option was scrapped in P3's initial version, they decided to integrate it into Portable.