Is using hot water to make chapathi dough a good idea?
Yes, using warm water helps keep the dough soft and also helps with the kneading.
Hot water denatures the proteins in the dough and also apparently makes it harder for gluten to form. I found this from this really beautiful video by Bong Eats. They recommend using boiling water to make the dough. I've tried it a lot of times, and it does work. It makes kneading easier, and the dough is softer.
Another tip: If you consume dairy, you can use a little yogurt while making the dough. That brings in the Lactobacillus bacteria, which slowly ferments the dough. That makes the chapathis soft and helps in keeping them soft for longer.