I'm assuming you're addresing more people than just me with your post @Karlotta
Missiles were terrible back in the day when most newbies used them. Even before I began le derp training shooting a buoy at 3 AM due to the lack of more opponents in connecticut, I was rarely hit by them, and the same goes for just about anyone else.
The current sidewinder works well in every aspect other than CMs not doing anything to stop them. Once that's fixed I couldn't care less if everyone uses it. Again, people are not entitled to win, including all good players and obviously me. Personally I see the whole "I would have won 1v5 if they didn't use sidewinders" as more skype benting than anything, just like I say "I would have won if I had fought 1v3 and not 1v4" or "if this guy hasn't shieldrun 1v6, what a prick". Add more swearwords and you'll go pretty close to my daily reactions from when I could play the game without 6% loss.
I would be completely okay with people using 6 sidewinders as long as the ammo is shared by all the launchers.
I also understand that many people don't want to be the Flash of Freelancer and forever and ever win every last thing a player can win until they die of old age, but if they face someone who does, no matter how much you tinker with loadouts, ships or balance, they are most certainly going to lose. And that's independant of sidewinders tracking through CMs. Now, if you are talking about groupfights (be it 1vX or XvY) things change. If missiles being mount-able in every slot, sidewinders being left alone (fixing the CM issue) and whatever other changes you see fit are going to make the other players more useful or at least feel that way so they enjoy the game better, I'd like to see those changes.
Again, players are not entitled to win. If someone thinks that because he is good he must win every 1v1 and just about any groupfight vs newbies, then they have come too far from their beginnings. They probably are going to win any 1v1 with a newbie and that's how it should be if they are better, as RNG should not be the determinant factor, but let them spam missiles in groupfights all they want. It certainly won't be fun for the person being ganged upon, but hey, might as well test it.