Now that I have more time, I can address a couple of other things.
Apple is like any other company, and they don't want to have to admit that there's a problem with any of their products. That's expensive, and so they want to keep things quiet. It's a game of financial calculus that every company goes through. If the estimated costs of doing nothing exceed those of a recall, they'll do a recall, otherwise they will steadfastly refuse to do anything. Auto makers and drug companies are the masters of this.
But if you figure they're making parts in lots of 10,000 or so, testing each part individually before it leaves the factory just isn't a viable option. It'd be too costly and time consuming. So they use statistical sampling, which means that sometimes a bunch of good parts will be scrapped, and sometimes a bunch of bad parts will make it into the wild. Just the nature of the game.
As for the trackpad, it can be replaced apart from the top case. It's kind of a pain because they have these tiny little PH000 screws holding the thing in, and nothing strips like tiny little philips screws, let me tell ya. It's really fun on the older style MacBook Air's, where there's 13 of the little buggers holding the display assembly on. One or two strip, and it's more fun than a barrel of monkeys sorting it out. But the whole unibody name is kind of a misnomer with the laptops. All they did was flip the construction order on its head. instead of a bottom up construction, it's a top to bottom method. For MOST repairs this actually simplifies things immensely, but it makes things like display assembly replacements more of a pain. None of this really matters to non-techs however. It matters to people like me, and non-Apple AASPs who end up being used as Apple's bad guy. We're the ones who have to tell people that this or that can't be covered, and then they go whine to Apple who will play the white knight and fix it.
If you think you have a love-hate relationship, you should go to a local AASP and talk to some people.