It isn't important, because words are one of my favorite things--instead of asking why the sky was blue, I was one of those children who wanted to know why grandma said K-nife instead of knife. I loved words with the letter 'q' (btw, in one of my linguistic courses, people shared the letter they fell in love with as a child--q, x, z, k, p, and w were the letters). It is one of those linguistic quirks that I find so very interesting because my MA is in linguistics and dialects were one of the areas I found fascinating to study. I love talking about words. I thought perhaps there were others who would find it fun.
The word is reflective of the immigrants who settled in the area. Where I come from, and where I now live, the word gravy isn't used for the sauce one puts on pasta. For those who live in areas settled by Italian immigrants, gravy is to them what sauce is to those of us living elsewhere and who grew up in communities made up of immigrants from other areas. Another one is bars vs. squares. In New England, there are a lot more verisions for chowder than you'd find in Nebraska. Not a lot variations for chili in MN, but head on down to TX! Church cookbooks and Jr. League cookbooks are a great source of these regional differences.
Language is reflective of culture and "hotdish" is reflective of the tradition of barn raisings, meals that could be stretched to feed a large family, neighbours stopping by if they haven't seen habitual activity at your house for three days (this happens when I'm in MN and my dad is out of town and not walking his dog--the neighbor usually comes by to find out if s/thing has happened to my dad because I'm the one walking the dog). Hotdish is a regional word reflective of the Scandinavian immigrants who settled in the areas mentioned. I just find it an interesting "food" word. Not important, just a regional linguistic anomaly. My grandmother's handwritten cookbook has hotdish recipes--pre-dates when casserole entered the English language in the '50s. She lived almost all of her life 18 miles south of the US-Canada border. In a region settled by Norwegians and Swedes.
You were born in MN, didn't you eat hotdishes before you moved to CA, Kayelle?