I have to step in and say a few things...
First off, as an ork player some of these things are pretty off....
If the ork player gets to go first, and he is any good, a huge amount of deep strike real estate is gone.
If you are heavy drop pod, a demon, have a lot of deep striking units in your army, and I'm deploying first, then I'm deploying my lootas back a bit in my deployment zone. I'm placing a unit of shoota boys in front, and then on my first turn of movement I'm placing my shootas in such a way that you just aren't going to get a heavy flamer, or any 12" shooting on my lootas on the turn you land.
It's not always foolproof, and if there is a deep striker that can get close more consistently than anything else it is a drop pod. But let's just take units that deep strike then shoot 8-12" right out of the 'loota answer' column.
Lootas get solved a couple different ways.
One way is to make yourself loota proof. 3+ and 2+ armor saves, toughness 6+ with 3+ armor, armor 14 vehicles, 60"+ range shooting, barrage weapons
If you don't make yourself loota proof, then you'll have to be able to hurt them.
Here would be my faves to hurt them.
whirlwind (incendiary only)
lootas
snikrot+kommandos
space wolf scouts
an assault unit in a land raider crusader or redeemer
empty land raider redeemeer
stealth team markerlights followed by mass missile pods or submunitions
mass mortars
mass shadow weavers
mass lobbas
Particularly useful combos include anything that can whittle down lootas followed by weapons that cause pin tests.
Here's a loota quiz for you...
you shoot 15 lootas down to 7 on turn 1. They pass their morale test. On turn 2 do you...
A) shoot at the 7 man loota unit again and wipe it out.
B) shoot at a fresh loota unit, taking it down to 7 and hoping it fails a test.
C) shoot a little bit at the first loota unit, making it take another leadership 7 test, and then kill 6 on the fresh loota unit, hoping it fails a leadership 9 morale check.
my answer is A. Lootas are full of overkill, their weakest link is that they can only kill one thing a turn. If things go well for their morale tests, you could end up leaving them with 3 loota units to spread fire every turn, even after two full rounds of shooting at them. Even 6 or 7 lootas can wreck a vehicle or hurt an infantry unit quite easily.
Assault units that don't appear at table edges or assault out of armor 14 transports can be loota proof, but they can't be loota answers, either their transport gets blown up, or they get intercepted by shoota boy screens.
Just keep in mind that you can win games without touching lootas, depending on how your army is built.
example... an army made entirely out of wraithlords, wraithguard, pathfinders, and jetlocks could just pretend that the lootas didn't exist, put some heat on shoota boys, and win objective games handily.
A rhino rush, or grav tank rush, or monstrous creature army will have to find an answer, or at least hurt one or two of the loota units in the game to make it through intact.
I'm just patiently waiting for elite slot thudd guns for imperial guard. I think if
GW can make an infantry based guard army that can outshoot a 45 loota/9 kannon/9+ big shoota list, then ork players are going to have to make list adaptations or concede all of their games against
IG. If
GW doesn't do that, then I think we're gonna keep seeing 45 lootas

.