I am bad player but from what I tried playing LRM missiles, I have to aim much more than with normal guns.
This is from view of rookie player compared to good players who comment here.
With my normal guns I just see someone, I aim at them, push button to do damage and then one of us goes to hide again.
1000+ range and ECM or stealth armour no problems, all I have to see is a little bit of arm from behind corner and I can shoot.
With rockets you have look around all the time, waiting for red squares, then you need to instantly look at it and hold your aim perfectly in center.
Yes it doesnt have to be perfectly on middle, I know, but that lock can sometimes behave little silly, especially if you or your target is moving and I think mech size or shape has definitely something to do with that, this is just conspiracy from me

but when I was practicing in testing grounds it definitely feels like some mechs get locked while aiming at the same place in the red square on other mech doesnt work.
This is already twice as much work for me compared to normal guns, and its not even the end!
When you finally get a lock, now you can shoot, compare this to normal where you can just shoot as soon as you see something.
During this whole time you have to aim again "
perfectly". And its not same aiming like with laser, your laser will still do damage just into different part, but with missiles right when you lose lock for even moment they just collapse to ground doing no damage.
Now there is tons of other problems that dont exist with other guns. Your missiles randomly deciding they want to hit wall right in front of you, instead of going above. If you want to shoot around corner, you need move your cursor away from your target, but also not away because you lose lock.
Imagine shooting AC/something on moving target. You need to aim in front of them, but if you take your aim away, you suddenly cant shoot your gun. This sounds very silly, yet its expected from LRM.
Then you have situations like ECM or stealth armour, ECM and stealth armour should either be removed from the game or made available to everyone

.
Only gun that is disabled by these are missiles, I dont need red square to shoot lasers.
You have person poking around corner or behind hill, you use your laser TAG to spot them, but to get lock on you need to aim at the center, but center is behind hill, so you aim your TAG at ground, but if you aim your TAG at ground, you cant target them.
This was so frustrating, and that is still just getting lock, thats only 1/3 of actually hitting someone with missiles.
Before you say just bring PPC/NARC/TAG which other weapon needs you to bring another weapon just to be usable.
I have fancy mech I build but cant use it most of the time because I cant fit TAG on it and have to sacrifice one missiles slot, which could be even 15+ damage to bring narc and some lowly 10 rockets for it.
If only solution is standing in the open so I cant hit walls or trees, 500 meters from my targets, doing all my locks myself, then it completely defeats the point of LRM.
I can just choose one of dozen other weapons that do their work better.
I once asked question in game about LRMs and someone told me to just learn how to aim and play proper weapons.
While I was sitting there, sweating, head so close to my notebook I was breathing on my screen, shaking and my hand cramped and hurting from swinging my mouse around whole match.

Only to shoot 2000 missiles and doing 100 damage.
No LRMs are absolutely not zero effort auto aim weapons.