One, its often atrocious-looking when they force so many. Two, it helps maintain a certain character for the mech. Three, you get a chance to 'cool' a little between half-volleys of missiles, allowing your mech to run cooler for those 60 LRMs you've just thrown versus another 55 ton mech that has 3 sets of 20 tubes. It also forces enemy AMS to fire for longer durations, consuming more ammo or generating that much more heat in the case of LAMS. In both cases that is very advantageous.
If you lose a lock when the first ten missiles leave the launcher but achieve it prior to the second volley from the same launcher, the second set will home in. The reverse is true, too. By this I mean you can reacquire the lock and the half that fired when you had the lock will home in. The half that fired in between is lost, sure.
(This trick is also practically required for "Corner turning LRMs" that will loop around obstacles or deliberately hit enemies from behind when firing from in front of them.)
But if you lose the lock just prior to hitting the button on a 20 tube launcher, all the missiles will go stupid and can't be salvaged and will not go after the target even after reacquiring the lock.
So in addition to running colder due to being able to take a breath and cool between half-volleys, you can save ammo from those accidental misfires due to lock lost... and another neat ability for those that are dumb firing LRMs, you can spread the volley of a single launcher between two separate points to cover and suppress two specific areas that are frequently "popped" from by would be pop-and-squat sharp shooters to suppress them.
In other words; TL;DR: It would lose a lot of tactical advantages for players using the mechanics of multi-volley firing single launchers. (Yes, it would also lose a few flaws associated with it, but give and take.)
Course, we could always have our Wolverines look like this instead.

But I'd rather stick with the I hope it never changes.
Edited by Koniving, 03 May 2018 - 02:58 PM.