I agree we should avoid human traditions, however, that does not legitimize the old covenant feast days as normative for Christ's Church today.
Questions that need to be considered:
Why is it that passover could not be attended by non-circumcized males?
Why is Passover specifically tied to blood sacrifices?
Why is it that "tabernacles" was specifically tied to "gather[ing] in the fruit of the land"? (Not any old "land")
Why is the Day of Atonement specifically tied to an "offering made by fire to the Lord"?
No one celebrates these feast todays as they are commanded in the Levitical code. And God never commanded His people to keep these feast in any way but according to the Levitical code. E.g., a "passover" service that deviates from Exodus 12, Numbers 9, and Deuteronomy 16 is just as much a human tradition as Christmas; "You may not sacrifice the Passover within any of your gates which the Lord your God gives you; but at the place where the Lord your God chooses to make His name abide, there you shall sacrifice the Passover at twilight, at the going down of the sun, at the time you came out of Egypt."
"You shall not add to the word which I command you, nor take from it, that you may keep the commandments of the Lord your God which I command you." (Deut. 4:2)
Modern, accommodated observances of old covenant feasts are obviously human additions to the Word of God.
I think you folks are kidding yourselves into believing that these were not uniquely Jewish feast days foreshadowing the coming of Messiah, and not to be continued once He had appeared.
Nice to meet you...not KC, but Grand Rapids. KC is my initials...:-)