Is just a plain black box. Every neural in this network has couple of inputs, sum up them with some multiplicative and if treshold is met it just make an output to another neurals.
Thats it. All.
You can train neural network with data, it even work and give enough good results. Why it's black box?
When neural network gives you an answer that this input = make decision A, this mean that it's output is for example 0.431 which is similar to output of other decision A examples.
You have NO idea why you should make this decision. It's AI based not on any type of conditions, just summing up and multiplicate by some numbers.
It works great for pattern recognition, it work for classification, but for AI in games? Not that much.
Games AI is in 99% of the time condition script based, with random elements. We use random to either force AI to change behavior (so it look less scripted, more "free") or to simulate non-ideal situtations, like awerness, aiming, etc.
Things like avoiding aoe by AI are very hard to implement and they could work only in limited scenario. It's easier to do it on grid/hex type of map, it's hard on free movement type of maps. It's easier when aoe are limited, very hard in gw2 where amount of aoe (mostly those staying for xx time) is quite huge.
First it makes melee bosses problematic to script, because priority should be on attacking players, not avoiding. Those bosses should move very precise way and smart way, trying to find a spot in which there is no aoe but there is a range for attack.
It is also connected with target switching, which can lead to some abuse. It's also very hard to implement algorithm for precise movement. Why? Because you need to calculate in real time a lot of things. For human finding way between 2 aoe and goind in some curve is a simple task, for computer is a lot of work to find this optimum way.
Also there a plenty of moments in which it's impossible to avoid all of aoe. Sometimes it's better to stay instead of moving, sometimes it's better to go right because aoes there deal less damage, etc. Huge amount of work for ppl and still probably end result wouldn't be that great in general.
What can be done imo.
100% pure melee bosses should have more variety of moves. First point blank aoes or other types of anti melee moves. They shoudn't be random or "cheap" but telegraphed. We still want moves which can be avoided, we just want to avoid facetank.
Those bosses should also have anti ranged moves, leaps.
But imo best way to avoid stacking are moves connected with pressure. Let boss stick to one player for some time and attack him all the time. Player should be forced to dodge and maybe even run away. Connect this with some phases or whatever, maybe enrage, in which when boss get some player down in that phase boss get some special move etc.
For ranged boss it's simple. Implement AI in which they try to move and stay in range (movement need to be better, like going backwards and shooting to avoid stupid movement), maybe moves like leap backwards etc.
This should help with corner pulls, boss even when pulled that way should quite fast leap or move out of way.
Still sometimes it will be necessary to remake some maps to avoid "dead ends" like corners.
For trash mobs.
Anet has this type of behavior even implemented. Some dredge bombers like to move away from melee players. This should be implemented to every ranged mobs and improved.
Some melee mobs should prefer frontal attack, some prefer going back. Best way will be to implement "flanking" algorithm which isn't that hard, this should help with corner pulls.
Imo main focus on trash mobs should be made in way in which mobs avoid staying stack and instead try to flank player (ranged mobs going ranged). It still should be possible to fight stacked with mobs but only with good combination of skills. Pulls + cc + snared should be the way to force mobs stacked in one place.
Ambush is possible as you said but it's still random/scripted system which can be predicted. It also does not change much in gw2 because making open world content harder isn't really a good thing. This content should stay easy.
Making this type of things in dungeons could be good but could be also not good. It would make dungeons more random (sometimes you can kill those 2 mobs alone, sometimes you need to fight 6 at once) but personally I don't like difficulty being connected with random things. Let fotm be the best example of random difficulty.
Yes, ambush could be predicted. But note that that is a good thing, since being able to differentiate ambush from just a mob fleeing is a question of battle awareness, which should be rewarded much more than it actually is in GW2 (where it usually amounts to "red rings hurts").