why is it an ordinance we need in order to achieve the highest degree of heaven?
I’m not sure if you’re talking about the sealing ordinance or the endowment here. I’ll assume it is the sealing ordinance. Richard Bushman discusses the theological innovations of Joseph. I do believe the sealing ordinance was one of these innovations, and tying our salvation to a spouse is an interesting thing. “Neither is the man without the woman, neither the woman without the man in the Lord.” We need each other to attain our highest exaltation. If God is both male and female, I think the union of a man and a wife is an interesting way to view God (despite the patriarchal nature of religion over the centuries.)
I am still just wondering have the temple ordinances been something that has been required or done down through the ages or is this something that Joseph Smith saw as having value somehow in the theology he was developing?
Temple ordinances (meaning endowments and sealings) were not done though the ages (even though Joseph thought they were.) (Others may disagree, but I don’t see evidence for this from an academic, historical perspective.) Yes, I think it is something that Joseph Smith saw as having value in the theology he was developing. Greg Kearney really expounds on this in the Mormon Stories interview.