I would suspect that it's primarily a perspective issue, and if you shifted your vantage point from side to side, and up and down, you could make it appear to be just about any set of keys.

The backlight is just a light pointed up under the keycap, there's nothing terribly high tech about it. But if it bothers you that much, you're still under IW coverage, so take it somewhere and have it looked at. They can replace individual keycaps or even the entire top case.

And it doesn't matter if it's a $25,000 laptop, anything that is mass produced will have the occasional bad unit. That's just how things go. You have imperfect materials, so even if the process for making the product were perfect (and it's not), you will still have a few bad units from the imperfections in the materials going in. Also, the only reason it costs $2500 is because virtually every company out there uses what is basically slave labor in China. Apple pays people a bit better than the average, but we're still talking about people working like 18 hour days, living IN the factory they work at, and making about as much in a week as someone flipping burgers in the US makes a day. There are few, if any, labor laws, and those are rarely enforced... Especially since Foxconn, the company contracted to manufacture the parts, is a Taiwanese company operating factories in China, and if you follow geo-politics much you know that Taiwan and China don't exactly get along terribly well. As a culture, we in the west need to face up to the fact that we're too cheap to pay someone a decent wage to make the product domestically, so we hoist it upon oppressive regimes around the world which have absolutely no problem selling its people into indentured servitude so slake our desire for saving a couple extra pennies. We shouldn't feel particularly entitled to anything based on how much we pay for it. It's a false conclusion that price and quality have a direct 1:1 correlation. It tends to be true as a general rule, but there are plenty of cases of cheap things being equal or better quality than considerably more expensive (like HDMI cables for example), and then there are cases where paying a bit more does net you a better overall product... Like your 15" MBP vs some $500 netbook.

So, anyway, I bet if you try changing the viewing angle of the keys, you'll notice that the leakage of the light follows. Anything Apple might change, design wise, to fix that would come with a new set of issues. Right now, if a keycap comes off on your MBP, it's quick and easy for someone to fix it. If they sealed those keys to the top case, it would require the entire top case be replaced, and that is a lot of work on the unibody models. You basically rebuild the entire computer inside the new case. You take everything out of the old one, then transfer it over to the new one. That's a lot of work, and it also involves a lot of additional wasted materials. Not to mention what happens if the material they use to seal the keyboard compartment gets stuck under the keycap and then prevents you from being able to fully depress the key? Or suppose that material starts breaking down a couple of months in when it gets exposed to real world testing, not just lab testing, now you've got an even bigger problem on your hands because you have to figure out some new material to replace the existing one, then rush that into manufacturing, build up a supply, then fix (on your own dime) all the affected systems sold, pay labor out to AASPs that do the work instead of Apple Retail stores, not to mention scrap your entire standing inventory of the old part.

If it seems to be only one or two keys no matter which way you look at it, then make use of your warranty, that's what it's there for. You can whine and complain until the end of time here, but it won't get your system fixed any faster. Apple's warranty claim system is heads and shoulders above the rest. You can walk into any AASP or Apple Retail store, explain the problem, and so long as there's no obvious signs of abuse or liquid damage, that's it. The entire tab is picked up by Apple, and they have financial incentives in place to try and get AASPs to turn repairs around quickly, but also to make sure the repair is done right the first time.