1.) I think driving a standard transmission is a life skill.
2.) I like the feel of a direct connection. I'm not a fan of the slushy, rubber band feeling of an automatic. Even in my bloated, 3900lb Accord wagon with an I4 engine, when I need the car to be quick, it's surprisingly quick. My wife's meager Neon is the same way. It's startlingly spry and eager with its manual transmission.
3.) Control. I can hit the gas in first gear and drive it up to whatever RPM I want. Then I can ease off the gas if I want--leaving it in first gear--and slow the car down just using finesse on the throttle and engine braking. Or I can shift into second gear, or third gear, or neutral and coast.
Also if I'm on the highway, lets say stuck behind some slower moving traffic and I want to move over into the passing lane to get around them, but I'm not seeing too many gaps that I think I can wedge my car into without cutting someone off pretty badly. I can drop gears and get my RPMs up while moving slowly, then hit the gas and get all of the power down right when I need it and make a surprisingly quick and effective acceleration run into the next lane. I hate driving automatics where the best I could do was to dick around with the shifter and force the damn thing down into a lower gear, THEN try to pass because I know that the auto is slow as hell and if I stood on the throttle it would still take a full second to drop down one gear out of overdrive, then another half second to drop down another gear before I could even start accelerating--which is a small eternity when I just pulled out from behind a trailer truck doing 40, in front of someone else doing 60+ and flying up behind me.
Then--control again--I can leave the car in a lower gear until I'm completely done passing and settled back into the right lane, where an automatic would instantly jump back up into O/D the second I ease off of the throttle, taking away all of my power, so I might still need to stand on the throttle again before I'm finished.
4.) Engine braking. It's just handy, and since I actually know how to do it, I find it useful and take advantage of it at every opportunity. It's just one more thing that I have the choice of doing, or not.
5.) Fuel economy. True enough, there's not a huge difference between manuals and automatics today. In some cases automatics win out over manuals. But I still say that the manual transmission offers better potential. I know the lowest workable RPM my engine can pull off depending on what kind of driving I'm doing. I can work my shifting with all of my focus on fuel economy. Just creeping around town I can be up in 5th gear just moving around at 35mph (or so.) I'm also constantly alert to what's going on around me, so I can quickly drop gears and accelerate when I need to, moving around seamlessly instead of thrashing the gas pedal and trying to manipulate my transmission into shifting into the appropriate gear for the situation while I wait.
6.) I think it makes a person a more attentive driver. Non-standard drivers tend to think that if you drive a manual, you're hunched over the instrument cluster with your eyes locked on your tachometer constantly monitoring your revs, or having a staring contest with your shifter to make sure that you're putting it in the right gate. That's just asinine. Newbies might do that, but it doesn't take long before you get the right feel for it. After that you can tell by the sound, the feel, the overall feedback. Just like you don't have to stare at your speedometer to know about how fast you're going, and you don't have to stare at the floorboard to make sure that you're not stepping on the wrong pedal.
On the other hand, I do find myself watching traffic much more closely becuase I'm constantly watching for information to help me predict what I should be doing next. What gear I should be in, or if I should start getting ready to engine brake. Yeah, anybody and everybody should be doing that anyway to have a better feel for the traffic flow, but when you have more at stake, it's more important. You don't want to be crawling along in top gear at 30mph while traffic is pulling away from you, and now you have to do more to catch up than just hitting the gas.
In other words, you're more in tune with the road, the car, and your surroundings.
7.) Because they "F'n" want to. That should be reason enough.
There are tons of reasons against it. Nobody makes you do it. And since manual drivers are in the minority in this country, they'll probably be relatively extinct eventually anyway, and those of us who just like driving a manual simply wont have that option anymore. At least not unless we want to drive a sports car or a subcompact, maybe.