Here, should "so" be dropped?
Please read this: It is said that a literary work reflects the age when it was written. Forty years have passed since "The Dwarf" first came out. But unfortunately, around us, we can still see so many marginalized people like the evicted family in this novel.

Do you think it's better to drop the word "so" at the last sentence? If so, could you tell me why?

Question

Here, should "so" be dropped?
Please read this: It is said that a literary work reflects the age when it was written. Forty years have passed since "The Dwarf" first came out. But unfortunately, around us, we can still see so many marginalized people like the evicted family in this novel.

Do you think it's better to drop the word "so" at the last sentence? If so, could you tell me why?

Answer

Yes, it is better without the 'so'.

In spoken English, 'so' before an adjective or adverb is used simply as an intensifier. 'I'm so sorry', 'We're so tired', 'You did that so well', for example.

In written English, it's not quite the same. If you use 'so' before an adjective or adverb in a written text, you expect it to be part of a specific construction, for example with 'that' followed by a phrase indicating a consequence:  'We see so many marginalized people that it seems impossible to imagine a solution to the problem.'

Answer

you can drop the "so" if you want to sound more professional or formal.  The use of so here is only for emphasis or to convey a sense of more casual speech.

Answer

"So many " altogether is considered an adjective in English .
Using "So many" over "many " is just to call attention and point it more out. Intensifier as Suki mentioned .
I personally think ,that using 'so ' is a good choice as a literary style creating a certain emotional effect. 
It intensifies the feelings of pity and sympathy you could have for such people and families !