So I had written up a post prior to this one but it was removed because I was being a bit too mean, so this is my attempt to be more constructive about it.
In general I cannot say that I dislike the auto-play mechanic, as I have used it very frequently leveling up and completing trials/dailies etc. It's useful for it's purpose which is to basically automate a lot of the busy un-fun part of leveling which is "the grind", allowing you to look away and either multi-task or just sort of effortlessly go about your day while leveling. It's basically a bot that isn't illegal to use. One might wonder occasionally "If I don't have to pay any attention to do a thing, why even have it in the game", but in any case I'm not here to talk particularly about the existence of auto-play, but the flawed behavior it encourages later on in the game for higher level groups, pending your class/situation. I'm going to go over a few of the things I've experienced.
1. DPS path Warriors who spam chain on CD
I am mostly playing Gladiator so I notice this one most frequently. This is a multi-faceted issue because in some cases it's not even auto-play, sometimes the Warrior in question just thinks it's a good move or useful for grouping and doesn't realize he is completely flipping the bird to the actual tank, and potentially his entire group pending what disaster that could occur as a result of his use of the ability. However I would like to assume that most Warriors doing this are only doing it because their auto-bot makes them do it (I seriously hope). If not, then please, please, please, if you are not a Gladiator, remove chains from your skill bar. Please. There are better moves for DPS that don't require chains to take a spot on your skill bar.
2. Shepard Mystics who auto-play dungeons
This has so frequently led to wipes in the groups I've had...that I now role confirm and boot if the healer is not present. I *may* give a pass to a DPS on auto-play in a non-heroic dungeon, because a lot of times their resulting terrible DPS can be inconsequential to the completion of the fight so it isn't a big deal, but the healer leaving the auto-play to do all the work is not good enough. I have died to bosses several times, slowly, because the appointed group healer is auto-playing and simply just doesn't heal me in time or enough. Similar to point #1, if this is a case of the player and not the auto-bot, that's even worse but it's a different problem altogether.
3. Any class who auto-plays in heroic dungeons
I'm not going to say that these dungeons are that hard, but they aren't so easy that the auto-play can do them properly. Similarly to point #2, I now role confirm as a "ready check" and kick those on auto in heroic dungeons. The mechanics in heroic dungeons are often more meticulous than the auto-play is capable of managing, and it often results in these players just dying early in the pull, meaning a potential party wipe or an extremely long boss where wiping just makes more sense to do anyway and restart. Do not use auto-play in heroic dungeons. Do not do it. It's rude to your group to lock yourself in to a mediocre gameplay style that will die almost immediately on any boss, so don't be surprised if you get kicked. This brings me to my final point...
4. Auto-play is "bad-play"
I won't belabor the issue here, auto-play is basically "bad-play". The DPS is sub-optimal, and it doesn't follow fight mechanics. It doesn't even use the abilities as quickly as they are available, it is slow to use moves off CD. Essentially, if you are on auto-play, you are imitating a very sub-par below average player, maybe worse. This leads to a few things...
a. You make the group DPS lower
b. You (likely) die, making the group DPS much lower.
c. You are unable to abide by mechanics, making things tougher for the healer because of the resulting extra incoming damage.
You are essentially turning yourself in to a dead weight that makes it harder on everyone else. You are asking to be kicked. So I do. If I see a person on follow, I will role check, and if there's no confirmation in 5-10 seconds, they are gone and I will find someone who wants to be there.
So that's really it. Auto-play is useful for monotonous solo-activities like Trials, questing, dailies, and the like, it is not for subjecting your dungeon parties to a completely uncommunicative, mediocre player who is incapable of performing their role properly. Keep auto-play where it belongs. Don't use it in dungeons, unless of course you're being carried in some low level dungeon by higher levels, then by all means, do whatever you wish, but this is obviously not aimed at that situation.