Yeah, seriously about the stay and goto stuff. They should stay put, root themselves and just attack only whats in range. If they get knocked out of range they should return asap roughly to where they were. When fighting in a big battle with AoE's I like to spread my troops around a bit just on the edges of my supremacy so they don't all get canned at once. But... since they won't follow my orders its pointless at the moment to attempt any sort of real strategy (the point of the archetype..). Even with an extreme melee set like Necro there are times I'd like to have them sit on the edge of melee and dark blast / vomit into the mix. Its especially important on Mercs where you have generally weak defenses, mediocre resists, and long-but-narrow style aoe cones. Positioning is everything with them.
Yeah its also annoying when one of your pets runs off like a loose cannon and agros a bunch of mobs, ignoring your commands to fall in... it makes you look like a moron even though its not your fault. You get some other archetypes hating on you for that sometimes -- don't blame us!
Arrr, nope. Stay does not work like that. The ranged pets still run into melee to do their pathetic little brawl then (that is best part) they stay put there at melee range for the rest of the fight. I have just tested it on my bots and thugs: they still run in. Test it for yourself. You might be right if the pets can finish them off fast enough before the ranged powers are all in recharge. Try to fight a bigger or tougher mob. The brawl will always find its way into the attack train. It is the pets attack AI; can't deny it.
So I am not sure what you two are talking there and they STILL run in despite the 'stay' command. They never 'root themselves', unfortunately. Besides, unless they are in Aggressive stance, which you will loss your BG mode, they may stop attacking if they are not getting any return fire. So the pets will simply stand there if there is a good tank in the group holding all the aggro, or the mobs are all being held down by a someone.
Also, pets do not return to the MM as smoothly as you described. That is even more so in maps that are full of obstacles (like warehouse map) and maps that are very narrow (like caves). The pets movement are very erratic. They may jiggle a bit trying to figure a way then soon start to attack.
I know a few of my friends stop playing MM altogether even though they really like the AT. The 'run-in', or more generally pets' movement AI, is so fundamental a problem to MM. It is really upsetting that it is not been fixed yet.
Edit:
I have noticed it for a while now: the Vanguard MVAS can hover. It actually follows the summoner a lot closer than all other MM pets. MM pets have a tendency not to jump over small obstacles: like stair railing for example. If it is not over certain height, they tend to find a way around it instead of over it. They have no problem with the big ones like a wall or a cargo. So oddly enough, they are often struck behind or between small innocent objects.
In typical warehouse map, there a certain corner junction (the 90' turn from one corridor to another) where there is a zig-zag ramp on one side leading up to a small platform half way up that junction. When my pets go up there, quite often it is impossible for them to come back down again: they simply cannot jump pass the railing back to the ground level - they are running around back and forth on the platform. I suppose adding hover to some pets would be a solution (it might look odd on Ninja and Thugs). But after seeing the MVAS simply glide over all sort of big and small obstacles, taking the most nature and direct route to the summoner, I cannot help thinking how good would that be if MM pets can do that. Indeed one of the many salient problems that need fixing is the pets' ability to go over obstacles - particularly the small ones.
If not Go To then Stay. Stay should make your pets stand in one spot. If something comes within range then they can attack, but not move. Stay should work like a rooting effect. Instead of letting them run up to it. I honestly think thats the "run-in" code conflicting with the stay command. It's that specific code that should be removed and the control additions i suggested in my OP should be added.