I don't know, but it is hard to become Catholic too, as I've learned. I don't know why that is either... I think that if your sure your sure. I mean I did alot of study for years on my own, prayer, etc. but had to go through everything anyway, which off set the time frame that would have been most advantageous for me to serve in a cirtain way, namely, to be a nun. That's fine though because I've finally moved on and now I finally have a new interest and that's to be a ghost hunter! Who knew?!
Because everyone need not be Jewish in order to have a share in the world to come. ALL the righteous have a role and a place. The Jews were chosen, I was taught, not for extra privileges, but to bear extra burdens. So, it's a big commitment, and the rabbis want to make certain that those seeking to convert understand this and are sincere. That said, converts have always had a part, from the earliest of the scriptures. And once someone converts, they are fully Jewish.
because theres more to being Jewish than the religion
its also an ethnicity so if they kept including more and more outsiders the Jewish ethnicity would eventually be lost
We feel that if someone wants to convert to Judaism, they have to truly want it. To put it more simply, Jews have always been more concerned with "quality", and not "quantity" as some Christians and Muslims use today. For example, "we are the biggest religion on this earth!" "So what, we are the fastest growing!". Those arguments serve no interest to Jews.
Also, consider this: I could just say one sentence, and I would be considered Muslim automatically. Does that mean, truly, that I'm a Muslim? I have a little story I like to tell: When my Muslim friend and I were little, she told me to say that sentence some amount of times. Being little and a little ignorant, I said it, and then she was elated and told me "Your a Muslim, now!". Compare that to a convert I knew, who had to go to a rabbi thrice to ask him to convert her, and then she had to go through a two and a half year process before she was considered Jewish. Do you think she would go through all of that, if Judaism isn't what she absolutely believed in?
Edit: Mariasdawn, we are certainly NOT an ethnicity. We accept converts from any ethnicity, thus we have ethnically Chinese Jews, African Jews, etc.