I often feed my daughter who is almost 3months before she "cries" for it. Crying is the last sign of hunger, I'd rather she didn't have to cry for her meals.
Every baby is different. Some babies eat regularly like your kids did, some will cluster feed (eat continually for up to 4hours) and then sleep for a long time, and some will eat seemingly constantly "snacking" all day if you will.
There is nothing wrong with this...it's just the way the baby is made. Your kids probably had the ability to hold 4oz in their tummies. My Nephew was a baby that could hold down his entire bottle, my neice was a snacker she never ate more than 2-3oz per feeding so she ate more often.
It's also possible that your nephew is going through a growth spurt so he's going to want to eat more often.
I guess don't blame the parents for meeting their babes needs the best they can.
as for not being able to get your housework done Have you tried using a baby carrier? Like a baby sling (a ring sling, or pouch would work well) they are fairly inexpensive and will allow you to care for your nephew and still get your chores done and deal with your older children.