Would it be grammatical to say:
Hers was also a good point to include a header specifying the contact person.
as opposed to:
It was also a good point she made to include a header specifying the contact person.
1.) Hers was also a good point to include a header specifying the contact person.
2.) It was also a good point (that) she made to include a header specifying the contact person.
Version #1 seems to be a bit clumsy or awkward sounding. It would probably only be acceptable in a context where "her point" is discourse-old information. This means a context where the speaker and addressee already know, or just recently heard, what her point was. The reason why I'm saying that "her point" should probably be discourse-old info is that the subject "Hers" is referring to "her point", and the subject often (or usually) holds old information (but not always, of course).
Version #2 is fine as is. It could be considered to be an extraposition construction, where the subject is the dummy pronoun "It". The extraposed element would be "to include a header specifying the contact person".
2.) It was also a good point (that) she made [to include a header specifying the contact person].
A non-extraposed version could be:
2.b) [To include a header specifying the contact person] was also a good point (that) she made.
There's also another version too:
2.c) A good point (that) she made was [to include a header specifying the contact person].
Some of the reasons why speakers and writers use extraposition is that:
In the extraposition construction, the extraposed element can be discourse-new information, and often it is. And usually it is preferable to have the new info near the end of a clause (e.g. not in subject position).
In general, a heavy element doesn't function well as a subject. And so, if the subject were to hold a subordinate clause, then often the subordinate clause is extraposed because a subordinate clause can often be a heavy element. And, also, it is preferable to have the heavier elements at the end of a clause.
Sometimes the non-extraposed version is not acceptable (i.e. ungrammatical).
In conclusion: Version #1 is kinda awkward (imo) and might not be pragmatically acceptable in some contexts. Version #2 is fine as is.
"Hers was a good point" on its own is grammatical but literary sounding. It depends on what register you're going for.
"Hers was also a good point to include a header specifying the contact person" doesn't sound right. You would have to expand it into two sentences or use a colon as mentioned above.
The first example is perfectly grammatical, but it might strike some readers as off because "hers" means "her [noun]," but the actual noun isn't established until later in the sentence. (Using a pronoun first and establishing the antecedent later.)
A more common use for "hers" might be, "I wasn't convinced by his point, but hers was very well made." In this example, you know that "hers" means "her point" when you get to it, and you don't need to figure it out retroactively as you continue to read.
In general, I find this type of construction somewhat distracting, as it forces me to backtrack and breaks the flow of my reading. I would generally suggest rephrasing in a situation like this, unless there is a reason for maintaining suspense. But at the same time, it's not actually wrong.
For example, "Hers was the most shapely, scrumptious-looking, firm but tender, beautiful T-bone steak." In this case, you might think the speaker was attracted to the woman, rather than her cooking. The end of the sentence might be an attempt at irony. (I'm not actually good at that kind of irony.)