Zoning was the main deciding factor in where we wanted to buy, and we did consider renting something temporary but eventually decided that being out of catchment in the long run would make us feel like outsiders with the rest of the school community. Also, the school we eventually enrolled our DS into is so hard to get into, they don't accept ANY out of catchment enrolments and they also can't guarantee siblings will get in if you move out of catchment. This is a Sydney school by the way, so I'm not sure it's correct as someone mentioned above that siblings having to be accepted. That's probably just a school policy that schools can choose to adopt.
I agree with what others have said about the social aspect of living in the catchment. I went to a high school that was about 40 mins on the bus from my house and I hardly knew anyone in my grade outside of the hours I spent in school with them. Then my family moved to another suburb where I could go to the local high school and I was all of a sudden spending time with friends almost every day, having sleep overs, study sessions together - it was a completely different school experience. I know it's slightly different with high school but I imagine even in primary, if you aren't local, it's harder to socialise outside of school, and playing sport for the local teams would also be more challenging.