Mechanical watches are designed for the intricacy (think "complications") and marvel of their movements and design, not necessarily for accuracy. If you want accuracy, get a quartz watch or an atomic one as you have. I've had my steel GMT-II for several years and it gains about 4 seconds a day. So? It's still a great looking watch, keeps time in three time zones at the same time if I want it to, and is rugged. Hopefully I'll be able to give it to my kid when he's old enough and if he wants it.
On the matter of accuracy, think of it this way: there are 86,400 seconds in a day. Even if the watch loses 15 MINUTES a day (900 seconds), it is still 99% accurate. How accurate should a mechanical watch with hundreds of parts, often hand-made, be?
You make some good points, BUT:
A. I wish my Breitling only lost 4 seconds a day, it loses 2.5 minutes a day
B. 15 minutes a day is crazy... there's no way
C. I get the whole "movement thing", but you gotta admit, if you pay THAT MUCH for a WATCH, wouldn't one expect an accurate one!