So when listening to the commentary of the first game in the Kramnik-Aronian match, they mentioned that Aronian wanted to keep all 4 rooks on the board because his king was safer so it gave him more attacking chances. I feel I've also seen other places where people talk about it being advantageous for one side to exchange a pair of rooks.

So, if you have a position with all 4 rooks on the board, are there any general factors that you consider when figuring out who gains from exchanging a pair of rooks, or is it way too situation dependent? Is it always that the attacker wants to keep the extra rooks on? Are there other factors as well (like something to do with pawn structure or which other pieces are present or material imbalance)?

If this goes nowhere and anyone wants to expand this to other rook talk, go ahead. There are positions with just one rook each or some imbalance (like RR vs R+B+N or someone being the exchange up) where it can be difficult to know who wants to trade rooks and who doesn't. Rooks are weird -- so strong, but so clunky, starting away from the action, but eventually gaining in importance.

i guess we are talking about positions with one open file that both can occupy?

The first question to ask yourself, can both players dictate the exchange or only one? Tension usually benefits the side who can release it more easily. So, say we have an open d-file and you have rooks on d1 c1 and control the d1-square with your queen while black does not have extra control over d8, be reluctant to exchange because you can always exchange and reoccupy the file while black cannot.