Just to be clear. The “they” whom you speak about is the Pope. Today, the Pope could change the rule and never allow a married man to be ordained in the eastern rites or he could allow married men to be ordained in the western one. Why does the Holy See allow it? Without delving into eastern rite history, or which I sadly know not enough of, my best answer is tradition. The Church embraces the traditions of Her many parts and only requires “lock-step” adherence to Her dogma’s/doctrines. There are many examples where you will see differences in disciplines (manner of dispensing communion, liturgy languages, holy days) between the various rites. The eastern churches even have a separate Code Of Canon Law, again because we are talking about rules and not doctrines. Since there is no harm to the faithful in allowing a married clergy in the eastern churches, the Pope allows it.
See above. On certain things, we are the same. On others, those which are not doctrines of faith or morals, the Church embraces the diversity of her many equal parts. Not every part of your body is the same yet they all work together to make your body well. Not every part of the Church is the same yet they all work together to form the Body of Christ.
I just recalled a priest friend who got asked once about feeling sorry for himself that he was not married. He said he sometimes felt sorry for us because we were. I am not sure every priest would call this a privilege or jump at it if offered. I will tell you that all of the priests I know embrace their celibacy as a gift and would not trade it for a wife.
P.S. - If we are not giving you good enough answers, perhaps you could post your questions in the eastern catholic forum?