it's not always about being a miserly or bad planning, lifter.
for instance, my 80-year-old Grandfather does this, as he is active and needs a quick snack when he comes in.
and say my family wants to take leftover pasta to work the next day... with a household full of people showering, shaving, putting on make-up, choosing outfits, ironing outfits, having something to eat, doing the dishes and scrubbing down the rest of the kitchen, cleaning out the litter box and feeding the cats, fixing and blowing the hair dry, doing laundry and folding laundry, vacumming the carpeting, going to the store, and so much more, all before 7:30 in the morning, there is little time to boil up a pot of water and cook fresh pasta.
if you have plenty of time, great. but lots of us are busy people and cooking up a pot of pasta each time you need some is not a realistic idea in my family.