What’s the point of XP and leveling up?

When you level up you don’t get to carry more grenades or med kits or have a higher energy cap (which you absolutely should). Your weapons don’t get a boost.  The only thing I ever notice is you get more cards from safe houses that well, stop at level 24.  So really,  there’s no reason for leveling up at all is there?  It’s not like you get to keep the coins when your purse is maxed and your cards are too, right?  What’s it for, really if you don’t get any benefits from it.