I'll be frank, I don't have a problem with escort quests or NPC support so long as one thing is consistent; I'm. In. Control. What this means is that whether I'm escorting an NPC or I'm being backed up by supporting characters, I want them to follow instructions. If I move, I want them to follow with me at a respectable distance; not breathing down my neck, but also not dragging their feet. If I tell them to stay somewhere, I want them to plunk their ass down on the curb and pull out a book they've been meaning to catch up on while I scout ahead. If there are enemies around, I want them to either stay behind me, take cover, or in the event they're support NPCs, hold their ground and give me cover, only maneuvering if something hits them. Furthermore, they should be following MY lead, which means they should only attack if I attack and only what I'm attacking or something that's attacking me. If I push forward, they should push forward. If I retreat, they should follow me back. If the NPC has healing powers that are limited, i.e. a first aid kit that runs out of supplies, or healing spells that drain energy, they should ask me first before using something to patch me up.
I think that anytime someone has a gripe with a given game's escorts or NPC support characters, it stems from what degree control is taken away from the player. Thinking back to the escort quests in WoW, the biggest problem I had is how the NPC's would blithely blunder on ahead, even if you had to stop for a second to eat some rations or put a bandage on or fight off some fucking monster that spawned randomly in your path that wasn't part of the prescripted escort battles. In Fallout 3, I love the personality of the companions, but by God, they are annoying when I'm trying to fight in an enclosed space. They'll detect an enemy two rooms away, and while I'm trying to loot bodies, they go wandering off on their own because they "heard a noise" and pick a fight before you're ready, robbing you of XP if the win and getting themselves killed if they lose. The worst part is when I've got too much in my bags and I can't run. I'm left impotently cussing at them and telling them not to get ahead of me while dragging my overfilled knapsack, stuffed with the guns and armor bits I can't bring myself to discard because they're either good for spare parts or I can sell them for enough to buy a post-apocalyptic concubine.
So in a nutshell, I'd say if game designers want to make escorts or support characters a big part of their game, they don't need to impress us with how well the NPC's can do without us; they need to impress us with how well they can follow instructions.