who vs that as a pronoun [duplicate]

Question

Possible Duplicate:
How to use: who/that

I have seen many writers using "that" as a pronoun in cases where "who" should be used. For example, a book author says

I apologize to those of you that are unable to obtain electronic copies.

Should it not be

I apologize to those of you who are unable to obtain electronic copies.

Or is it wrong to use the latter, in the modern context?

Answer 1

Well, why "should" who be used if English speakers often choose that? What's the reason behind your premise in the first place?