It makes perfect sense what you're saying.
My only argument is mainly that it wasn't done completely with performance in mind, as much as it seems financially-motivated. My assumption is that racing is the last on his mind since he's "poor".
I see the pro's of a lighter wheel, make some money back, and save on the reoccuring cost of maintenance with the tires. But to me, it's still ass backwards because it just takes away from the value of what the car was originally built or designed as. Especially with the MS3 being a limited availability/limited production vehicle. It's sort of a big deal imo.
My analogy for this thinking is sorta like, if you'd buy a Corvette but had a long commute and drove year round. So instead, swap to smaller diameter wheels, and all-season tires. Why even buy the car then if wheels and tires were going to dent the wallet?
Original Poster, no offense whatsoever. I'm just at a loss at the logic (UNLESS, you're auto-xing, drag racing, or otherwise using those 17's for a specific racing need, which you have stated is not part of the intentions). In a way, it's sorta like when people empty their bank accounts online with mods, then 6 months later they'll try to recoup their losses by taking another loss on a used performance product. $750 is sorta low too, when most are selling for $1000+.
$1000+! Damn. Still, I'm happy with the trade, I used the extra money to buy my wife a nice dress and build an HTPC. Both of which gives me much more pleasure than the 18" wheels.
My old car was a motor/tranny swapped STI. I had 18" Volks and Falken Azenis 615s. It made a little bit of sense because I went to the track occasionally, but it was still a huge waste of money. This car will never see the track, and it sees a twisty road 1% of the time. I could keep the 18" wheels and put some sticky rubber on them, but then I'd just be wasting them on open highway at 70 mph.
So why did I get the MS3? Because I like to fly around entrance ramps and then floor it. This isn't using the MS3 to it's full potential, I know, but I bought the car for the following reasons in descending order:
1 - price
2 - warranty, practicality, reliability
3 - straight line speed
4 - interior quality
5 - competence in the corners
This isn't meant as a dig, but I don't think the MS3 is an awesome car. It's the best in it's class by a fair margin IMO, but it's no Corvette, M3, GT-R, etc. The MS3, like my old STI but more so, is a hopped up econobox. It's got an extra 100 hp, some upgraded suspension bits, and an LSD. It's not meant to be a giant killer, it's a daily driver that is faster than the rest. For me, it doesn't "deserve" big wheels and sticky rubber like an M3 does.
I guess at this point in my life my car is more utilitarian than a source of enjoyment. I can definitely relate to those that dump money into their MS3s though, because I spent 5 figures on my STI and enjoyed every minute of it.