mazda3 had always kinda straddled a pricing line/segment. nicer to drive and more available equipment, but more expensive than a corolla. and not quite as nice inside but less expensive than the jetta (gen iv - v, latest gen is decontented).
side note: wonder if importing a new gen iv jetta turbo from mexico is difficult?
edit: why is the i-touring available with a moonroof but the s-touring is not?
Having driven both of these cars when looking for our new car this year, I challenge you to sit down in a 2014 Jetta, and then sit in a Mazda 3s Grand Touring and tell me with a straight face that the Jetta has a better interior. Quite simply the Mazda 3 is the best driving car in its segment, it has (on paper at least) the best fuel economy out of an engine with more horsepower and a real 6-speed auto or manual transmission instead of a CVT slushbox, and it has BY FAR the best interior in the segment. I don't even think you can find a vehicle in the compact segment that offers real leather other than the 3. It also offers a ton of features that you would have to move up into the midsize sedan segment to normally get ahold of like radar cruise control, forward obstruction warning, and has unique options only available on the Mazda like the Active Driving Display and the commander switch which I think works great.
There's literally no way you can line up a Kia Forte, Hyundai Elantra, Honda Civic, Toyota Corolla, and a Mazda 3, test drive each of them for an hour, and tell me that the Mazda isn't the best car there. I'm clearly biased because I own one, but I honestly cannot imagine a situation in which that would occur, because I've literally done it. The Mazda feels more like an upscale European hatch, and the others are just econoboxes.
Edit: Got ElFenix confused with OP so don't think I'm singling you out there heh. I don't know the answer to your question really about the moonroof. The S doesn't have a sport trim, and moving from the i GT to the s T deletes the moonroof but adds the bi-xenon headlights and the bigger engine, so maybe they wanted to offer a trim level without the moonroof but still have the bigger engine and headlights, and not have that trim level w/o the moonroof bump into the position of the i GT. Not sure on that one.