without claiming expertise, isn't the same for all religions really? if you want to marry in a Catholic Church you and your couple will be required to convert to Catholicism (if they're not already).
if you want to marry in some sinagog (or whereever it is where the Jews get married), you'll have to convert to Judaism
why should we expect Islam to be different?
i think the real matter is that a lot of people assume all Muslims are totally driven by their religion. needless to say, that's far from being a reality. to that extent, one can easily cite the example of marat safin who is a Muslim and yet doesn't seem too compromised with a life of religious fervor.
I don't claim expertise either, but I've always understood Islam to be more strict about a non-believer converting to Islam if the non-believer wishes to marry a believer. That's what I've heard from all my Muslims friends at least (I'm actually Singaporean, not Australian, in case anyone's fooled by my fake country flag). I have had next to zero experience with Judaism so I can't comment, but if I do marry my Christian boyfriend, it'd probably be in a church - and I have zero intention of converting (I'd also have a secular wedding for sure though).
Back to Islam - I'm of the view that there's no one right "Islamic way", so to speak (well, duh, really); it's just that this "conversion by virtue of marriage" thing has appeared to me to happen more frequently for Islam than other religions.
I see your point re. your last paragraph. That said, from my experience, the Muslims that I know generally tend to follow their religious practices more than the Christians, Catholics or Buddhists. When I say that I don't mean they wear a burqa or whatever (although many Muslim women in Singapore do); they just tend to follow certain rituals more than followers of other faiths. Friday prayers, for instance; on the other hand, some of my Christian friends barely go to church.
Of course, that may just be simply a matter of 1) I know more Christians/etc than Muslims; and 2) Islam has more religious rituals, maybe. I just find it interesting, this seeming difference between followers of Islam and followers of other religions.