'laughs in omni shield'
also
'laughs in point defense'
Seriously, the effect of salamanders hitting is great, but you only get it if your opponent is isolated and doesn't have much PD or omni shields. It's pretty easy to make them completely irrelevant with a little effort in the load out stage. In a fleet context salamanders tend to end up flying into the shields/PD of other ships because they target ships in the middle of the battle line. And they cost 6 OP, which is a lot. Definitely plenty of downsides.
Also, they just fill a very different role than other missiles, so it doesn't even make sense to compare IMO.