I couldn’t disagree more.

These are just a few examples. Of course, I’ll
go into them in more detail later.

Hungary: 

Magyar raised her just to be like him, which is why she uses
a more male language.

She has a complex over settling down, having previously
represented an equestrian hunting tribe, and has fears about her fighting
skills getting rusty [x]

Despite this, she’s described as “probably the manliest
person in the comic.”

She kicks ass. 

Belgium: 

Belgium’s ‘plainness’, as in she doesn’t stand out much in
comparison to surrounding countries, is what makes her more complex.

Any insecurity, weakness, or flaw adds depth to a character’s
personality.

Belarus: 

As one of the most neurotic and incomprehensible APH character
to unpack, she’s the antithesis of plain.

She breaks Lithuania’s fingers during a date [x]. It lasted three minutes.

Her obsession with Russia became so strong that she forgot
her own language.

Monaco:

This lady packs a strong punch in the world of business and gambling [x].

It was also just recently revealed that she fears losing her
nationhood. Remember that personifications represent their citizens and only exist
because of them.

As such, since most people in Monaco’s country are tourists
(transients) she doesn’t have many citizens to call her own. It’s the tourists
who create the need for her existence. 

The threat she faces is that if criminal
activity keeps increasing in her country, tourism rates will decline.

All in all, to say that the female nations are plain is
unwarranted. Even though some of them could definitely use more fleshing out,
they still have distinct personalities, quirks, insecurities, and weaknesses.

I think it’s important to recognize that it’s the quality of
their characters that matters most here; not the quantity of what we see.