That (5 lasers) would make it just nasty enough to tangle with at short range that most enemies aren't going to charge in just to get out from under the missile envelope unless they're built for brawling-range combat themselves in the first place, and doubling its ammo loadout isn't bad as a bonus. Plus, it comes at no net heat gain versus the ER-PPC and a 150% damage increase if all the lasers hit, giving you a bit more heat control to make up for the fewer heat sinks.