Because out of all people I know irl who had airpods for 2+ years, no one has reported any noticeable battery loss, let alone something as extreme as "only lasts 15 mins". I would be livid if mine lasted anywhere even close to that, but so far I am solidly in the advertised battery life range, even after 3 years of use.
Also, just fyi, it seems like your unit might have been defective, in which case Apple offers free replacement (regardless of whether you have any additional warranties or not)[0]. If you have AppleCare+ and your battery lasts less than 80% of advertised range, it is also free replacement (even if it wasn't a defective unit). And just the regular replacement regardless of warranty or anything like that is $49.
Where did you hear that? That's not my experience at all. Apple denied that there was anything wrong with my iPhone 6S that suffered from sudden shutdowns for more than a year, before they introduced the iPhone 6S battery exchange program. That was a pretty frustrating experience.
> And just the regular replacement regardless of warranty or anything like that is $49.
In Europe it's 55€ per Airpod, so the total cost would have been 110€ (the second Airpod lasted a bit longer but still not enough to make it through a movie).
110€ seemed like a steep price to pay for two new Airpods with an old charging case that will cost another 55€ when its battery inevitably dies.