Why am I interested in watches? 
I have always had a keen interest in mechanical things.  I can even remember when I was very young my father gave me a mechanical watch to wear.  I wore it for several weeks until my curiosity was too strong and I tried to take the thing apart.  I was surprised at how un-exaggerated the cartoons on television were - springs & wheels went everywhere. 
More recently my interest in Mechanical watches was suddenly sparked when I was window shopping some TAG Heuer watches in the department store.  I noticed an interesting line of watches which looked like antiques, but they weren't.  They had very classic styling, and what took the cake was a glass back on the watch (skeleton back) where you could view the movement.  The brand of watches was ORIS, and they were cheaper than most of the TAG range.   
The clincher for my interest was a conversation I had with a friend who was dreaming about collecting cars when he is older.  I was arguing that I like classic cars, but that they take up too much room, and pollute etc.  That was when it suddenly dawned on me that I would rather collect watches.  I hadn't even considered it previously, but I suddenly said aloud "I'm going to collect watches", and I knew that it was true.  Soon after I decided to get myself a decent Swiss Watch for my 29th Birthday. 
One more point that I should make is that the Internet has served to exponentially compound my interest.  Without it I wouldn't have been able to find out the huge amount of information that I now know.  My knowledge of brands, models, watches to avoid, features etc. has all been derived from the net.  The forum on www.timezone.com serves not only as a marketing tool for watch companies, but also provides critical reviews, and scientific & social background to watches and collecting etc. 
 

Why Mechanical watches? 
I will readily admit that a mechanical watch generally doesn't perform as well as a battery operated watch.  There are more parts that can go wrong, and they are more susceptible to shocks.  Servicing of the watch will cost more too.  A battery operated watch is sturdy, and reliable - except you don't know when the battery will go flat.  A quartz watch will probably have less longevity because of ageing of the circuit, contacts, etc.  Whereas a mechanical can usually have parts replaced.  Most modern mechanicals will provide the user with more than they require in accuracy. 
No matter what benefits of Quartz watches are listed, it is still UNDENIABLE that a good mechanical watch kicks any battery watch out of town. 

With a mechanical watch you have a living instrument, and a work of art.  Its performance changes with how you treat it.  They are like automobiles... in fact, they're better than automobiles!  No pollution, and you supply the power.  You get a minute, high-performance engine on your wrist.  It's also fun to think of an old swiss guy in the factory - tinkering around with the watch - assembling the pieces. 
 
Those watchmakers in Switzerland must be grinning from ear to ear thinking of how the watch that they're making is going to kick your ass silly.