"Basically" is not meaningless. If someone says to you:
Basically, you need an invitation to attend Fred's party.
That probably means:
You don't technically need an invitation to attend Fred's party, but you'd better damn well have one if you want to have any considerable chance of getting in.
And likewise, if someone's having a conversation with me and it runs along the lines of:
Man, that John Kerry is criminally insane, isn't he?
That last sentence means:
He's not criminally insane per se, but it's not too unreasonable to say that he is, because he's close enough.
So "basically" is a way of making a statement true in a simplified sense, but simultaneously recognizing that it is technically false in some (assumedly) insignificant way.
See? It has a simple meaning, basically.