One of the biggest assets a Defender had in the games was it's firepower. I don't think the rules make enough of it ,especially with it's cost, so that sounds like a cool fix. Stats and dials don't need improving. It just needs to do more for it's cost and linked guns could do that.
Well the TIE Defender still has Firepower. The cannon slot can give it HLC which makes 4 red dice at all ranges. The only thing is that it is the HLC Firepower and you can take it on many things that are cheaper. Shuttle, B-wings, MA-3 Scyks (although this has the least firepower with 2 primary). Still why would you take a TIE Defender when you can save 9 points and take a shuttle which has 4 more hit points. Sure the nerf does make it give up half the hit points on the shuttle but for 1 hit more you get an entire Defender. 3 Green dice don't save 4 hits usually.