Normal countries want to have relationships with one another, because of economic and technological development, healthcare cooperation, academic development etc. This is how countries are not left behind as the world progresses.
The countries that have to be explained are the ones who refuse to forge ties with certain other countries.
When we are dealing with the question of "Why some Arab countries established open diplomatic ties with Israel". We are actually asking "Why did some Arab countries break the ban on establishing diplomatic ties with Israel" - What pushed them so hard that they had to do something which was considered taboo for so many years?
The short answer to this question is "Iran" and the loss of interest is the seemingly unsolvable Israeli/Palestinian conflict.
All Arab countries which have established open ties with Israel are stable Sunni-Muslim countries, who wish to live in peace and fear the Shiite Iran and its radical agenda.
Israel is seen by those countries, as the single strong nation on earth that will never ever allow Iran to actualize this agenda. No matter the stance of any particular American administration.
I can explain more if needed. Please write in comments your requests.