As far as panties go, they differ very little from the form-fitting bathing suits that nearly all females wear. The
forbidden aspect of the one is that that garment is expected to be under some other garment, rather than visible. Girls in bathing suits are common sights at beaches and public pools. Yet, guys will sometimes value the forbidden peek at panties as more stimulating than the common sight of bikini-clad bottoms.
There are differences between the panties shots here and those found in
Agent Aika & other titles like it. The intent is different, as are the viewing angles. I recall seeing Nuku Nuku's panties as she somersaulted into action. Although Nuku Nuku clearly has sex-appeal, her panty shots have more in common with Misty & Uranu-chan's than with Aika's. They are more 'cute' than 'sexy'; however, this is my opinion. Innocent shots have tummies & bottoms, while sexy shots focus upon that area that lies between them.
Link provided lest some be offended
Alvin & his view of Misty.
Here is Misty's initial reaction to Alvin:

"Oh!"
The angle is nearly identical to the earlier shot before she pressed her dress against her legs, which were then as they are now, together.
Here is Nuku Nuku's nemesis, Eimi-chan, her secret revealed (she is an android):

Note that the angle is from above her rather than the view that Nuku Nuku would be seeing.
I provide a link here, rather than the pic itself (not that there is anything explicit about this pic, but some might object to it):
a closer view of Eimi's behind. Note that this does not show her underside, but only her backside.
These types of shots are clearly cute more than they are sexy. However, if we consider that one man's cute is another's sexy, we must conclude that some could be turned on by the sight of Misty's panties. The question then becomes how far towards intolerance & restriction must we go to protect children from those who would prey upon them? Clearly, it is impossible to ban everything that might stimulate pedophiles, without banning children from any public exposure ('exposure' not used as in 'naked', but as in seen).
It seems that the increase in child molestation & rape came close on the heels of tolerance of homosexuality; although it is one thing to show correlation, & another to show causation.