The one (generally) universal truth in all zombie movies is that pretty much all of the main character's companions are going to die nightmare-ish deaths and be torn apart by a marauding pack of the undead. Knowing this, expecting the remaining survivors in the Dead Rising mall to be able to survive their treks through zombie-filled shopping areas seems a little too optimistic. Even with their ability to use weapons, the AI is dumb enough that they'll often break off to try to kill more zombies, which inevitably leads them to getting sucked into the swarm and ending their short, meaningless existence on this earth. This is actually one of the few times where it's preferable to carry the NPCs, because - while you're left vulnerable - you at least have enough sense to try to run towards the actual goal. But usually they're stumbling on their own, holding your hand, wasting precious time that could be better spent whipping CDs at the undead.
When Peter Molyneux was hyping Fable up to impossible levels (that he would repeat again with the following Fable games, along with every game he's ever been involved with), you would think that the fact that Fable would include some of the worst, most irritating escort missions in videogame history would temper his own expectations a tiny bit. The escorts tend to run directly into danger constantly - towards enemies, right in the middle of the line of fire, and away from any safe place you might try to lead them. And worse, they babble incessantly, with voices that sound like failed auditions for an unfilmed Monty Python movie. Luckily, you can be a malevolent dick and murder them, and actually end up looking way cooler than a good guy would. Horns and ashy skin are always in.
Some games have bad escort missions, but they're somewhat forgivable because, ya know, they're just missions. In Amy, a horrible escort mission is actually the entire foundation of the game - but with a twist. Amy is a genius autistic child with superpowers, while you're a helpless, easily-killed adult who wears a miniskirt in the midst of a mysterious zombie apocalypse. So, it's kind of an escort mission in reverse - even though you're leading the charge, it's Amy that can actually take care of herself, and you're the one slowing things down (and you even begin to turn into a zombie if you stray too far from Amy). Speaking of slow, you move about as quickly as a slug who missed his morning coffee and is also pausing a little to wonder why a slug would even want coffee in the first place. It's hard to not feel sorry for Amy, who really got a crap bargain, getting stuck with you after the apocalypse. Really, like she doesn't have enough to deal with, being an autistic telekinetic child, but she also has to play second banana to someone who never thinks to kick off her high heels when being chased by zombies.