Since we're just speaking about hypotheticals if you dropped a long range missile that can fire across the board without issues to two damage dice you've pretty much ruined it against anything but the low defense ships. It would be the lowest damage potential of any secondary weapon and nearly a complete non-threat against evasive targets.

If the damage potential is the issue then something would be done to limit the maximum. Perhaps it should attack with four dice but only get to deal a maximum of one damage on a hit although that hit could be a critical.

This is all super hypothetical at this point, but I am completely certain there would be ways to make such a weapon appealing to some, without breaking the game. Maybe it is a missile that CAN ONLY be fired outside of range 3. Maybe it doesn't require a target lock, but randomly homes in on a target that you don't get to choose. Maybe it can only target large ships. Maybe it has a token and moves like a ship and can be shot down on approach. Maybe it ONLY attacks shields, or ONLY attacks ships that have no shields.

I don't know the canon of the expanded SW universe well enough to say which, if any, of these ideas might be appropriate to something that already exists. But from a strictly game design point of view, coupled with cost balancing, there's obviously many ways to make it work without ruining anything.