- the pilgrim thing is all made up anyway
- it makes more sense to have a feast to celebrate getting thru the winter than just right before it
- similarly it makes sense to stockpile some treats and extras thru the winter just in case (in the old days like of a famine)
- right now Jan and Feb are bleak awful fucking months with nothing to look forward to
- you see family during christmas anyway why do it in november too
Thanksgiving is specifically a harvest festival (one of the rare human near-universals) in which there is a feast held post-harvest (you know, when there is plenty of food!). Moving it to February would miss the entire point.