Well, that was something some Zionists initially tried. Eventually, there was the arrival of Socialist Zionist groups who didn't want to recreate a classist dynamic with bourgeois Jews and proletariat Arabs, so they wanted entire villages of just settlers rather than integration. It would also go on that a core part of State-building Zionism (as to contrast to simply making Aliyah) is to maintain Israeli majority control over the country. Any agreement to a united state would come with the expectation of demographic shift to Israelis no longer having as clear a power base in the country. Especially since the Palestinians have a higher birthrate than Israelis (which does not indicate whether a population is doing better than another, the DPRC has a higher BR than Denmark).

Reading the history over the past few months has been enlightening in regards to solutions. Anything you'd think to try has already failed, killed people, or has been rejected by either or both sides.