Apple is into customer experience, and for most customers, a more pleasant experience at the Genius part is a major part of it. Don't expect Apple to make things harder on Geniuses any time soon.
Getting the battery replaced in an instant at the Genius bar instead of having to wait a week would definitely be a better customer experience, don't you think so?
ignoring the fact that batteries have changed. The newer batteries keep a charge longer, and they have the same life expectancy as the devices they're in.
So, the life expectancy of the current MacBooks is just 3 years? This is the maximum how every Lithium based battery (except for the LifePo) I owned has lived. And it's no surprise if you understand how they work chemically. Yes, sometimes they will live longer. But the average is simply stuck at 3 years and it won't change much before someone brings us entirely new batteries.
This isn't 1979, when almost every computer owner needed to have a soldering iron on hand.
We're talking about replacing a battery here. Apple has shown how it can be done in older MacBook models. No need for soldering.