Not necessary, like you said, it's just a recommendation, that way you can access it again, if something happens. Some hardmodders also hide it under the battery cover, if that's what you want. Once I get mines sent out to be done, I'll go for ease of access like the charging port, think it looks beautiful if it's done just right. Instead of hiding it.

But that's just me.
Edit: If the hardmodder you talk to, make sure to talk to them about where you want it to be located, and maybe ask for examples of their work of those locations, if they have some, to show.