Did anyone ask them why?
As much as some people think it is because of some inherent unreasonable hate Jews have for Arabs, I think it's got something to do with all the murders. Maybe even with the one occurred just last week. Was this poll taken immediately after? Because if so it's plain that it's skewed.
People don't want to live with people who want to murder them. It's sort of creepy. Imagine you've got a sex offender living in your neighbourhood. Sure, just because he's done it before doesn't mean he'll do it again... but would you trust your child playing near his house?
If there were no murders or collaboration with Hizballah and Hamas, and incitement against the state by Arab MKs and all the other fifth-column activities they engage in, there wouldn't be much of a problem. Israel is a liberal society (the majority, that is), and is used to having to adapt to different cultures and integrate them into society. Jews from all over the world, of all cultures and countries and languages integrate to Israel every day. And Arabs' culture is similar to the Jews from Arab countries, so it's not entirely foreign.
Plus, Arabs in Israel are really not as bad as their representatives in the Knesset are. They volunteer for the IDF, and kill and die for Israel just like others. They get high paying jobs (albeit some discrimination exists)... they're an integral part of Israel. They've been there the whole time, so they are a part of the Israeli fabric and culture.
The only problem is Jewish Israelis' fears of being murdered by their Arab neighbours. Most Jewish Israelis are not as stubborn and nationalistic as the "settlers" and messianic Jews who live in Old Jerusalem who want to push Arabs out.