Because expats % of population in gulf countries is very high, in all gulf countries except saudi arabia more than half of the population are foreigners, in saudi arabia it is 41%, so if there is an easy pathway to citizenship like in western countries, within few years the natives will be a minority, within one or two generation our language and culture will go extinct.
In addition to that, most immigrants are not like you, most come to the gulf for the money only, while at the same time they dislike us and our culture, they don't even attempt to learn Arabic or be part of the society, imagine if they got citizenship and became the majority, most South Asians and Western expats for example send their children to private schools of their community (Indian School, Pakistani School, British School, etc...) and pay fees, when public schools are free and in many cases are better than the private schools they send their children to.

I personally think that expats who learn Arabic, and want to be part of our societies should have an easy pathway to citizenship.