While I am on the topic of coming up with reasons for the Yom Kippur prohibitions, I should certainly mention the following idea.
YK commemorates the day when Moshe finished praying for the Jewish people after the golden calf sin, and having achieved forgiveness, descended the mountain. On this day we too pray nonstop for forgiveness.
Furthermore, each of the five prohibitions we observe on YK was also, in all likelihood, observed by Moshe while on Mt. Sinai:
1) Moshe did not eat or drink on the mountain: "I fell before Hashem as before, 40 days and 40 nights - bread I did not eat and water I did not drink - over all your sins..." (Devarim 9:18)
2) He was alone and could not have had marital relations.
3) He was on a mountaintop in the desert, and would probably not have had the opportunity to bathe, even if he wanted to.
4) Nor did he most likely bring oil with him, so he could not have anointed himself.
5) On his first trip to Mt. Sinai, when Moshe encountered the burning bush, God had to tell him to take his shoes off, since the ground was holy. (Shemot 3:5) Presumably the ground was still holy on Moshe's later trips to Mt. Sinai. If so, he probably would not have been allowed to wear shoes (leather or otherwise) while on the mountain.
Given these similarities between Moshe's behavior and our prohibitions, as well as the thematic similarities and the fact that they happened on the same day of the year, it is hard to escape the conclusion that the prohibitions are intended to remind us of Moshe's behavior.
Rather, or perhaps in addition to seeing ourselves as like angels on YK, we can see ourselves as like Moshe on the mountain, begging for forgiveness, receiving the 13 attributes, and at the end of the day descending, having concluded a renewed covenant with God.