The differences between the golf and the GTI, and the MZ3 and the MS3 isn't that big. The GTI doesn't really look that much different than the golf. The reason everyone knows what a GTI is, because vw has been making it for 25 years, and the amount of hype surrounding the newest GTI has been huge. People see the GTI badge, and they know what it means. People see a mazdaspeed badge and they have no clue. Mazdaspeed models tend to stick around for one or two years at most then they disappear, so I doubt it will ever have the brand recognition that the GTI does.
Thats just fine by me, I'd rather not have to race a riced up civic every time I stop at a light, and as far as cops are concerned, it's just another mazda 3 hatch (and there are tons of those here in Ottawa!)