>>119040 (OP)
>The lack of shading,
Low standards and laziness.
>the attempt at trying to convey pretty colors through sheer shades of white with floral patterns and the like,
Lazy as well as low quality checking.
>the weird non-conform panel-sizes
Again, same thing, low quality in general
and low standards for quality check ups.
>the lack of artistic talent in basic human-anatomy.
Same thing again, low competition, low quality check. However this is case with most of shoujo i have read, i can't say it might be case for every shoujo out there, some may be genuinely good and have its own unique art style, i think its just because any fan fictioner run of the mil person who did not invest enough time in artist skilled, tries to make shoujo, and we get huge hands stupid body proportions which is not bad, but just uncanny in nature.