As Wedge009 said, the Piranha isn't meant to be a light fighter like the Arrow or Hornet. It's a scout, so it's probably comparable to the Ferret. Yes, it is specialized, but then, it's very suitable for the peacetime role it is intended to fulfill. It is fast, very manouvreable, and has more than adequate firepower for its role. Its Ion & Lasers should be good enough for most pirates and smugglers it encounters (although slightly lower firepower, it has twice the shields and three times the armor of a Dralthi), and if pressed, that Stormfire packs a punch. The Piranha has the speed and manouvreability to get on the tail of a Dralthi and chew it to pieces. If it encounters anything more serious than a couple of Dralthi, it just runs home to mamma (or those Panthers that are sitting on the flight deck just waiting for a serious encounter.
Taking on serious enemy like a swarm of Nephilm is NOT what the Piranha was intended to do.
p.s. if I had to 'update' a Hornet, I would imagine it would be similar to a light Tigershark - similar shields and armor (slightly better than the Piranha), similar firepower (2xlaser + 2xmass driver like the Tigershark or 2xlaser + 1xtachyon like the Dralthi) but probably slightly fewer missiles and without the charging mass drivers.