BINGO. I really don't think that "homework" is justifiable at all below the high school level.
I know of local kindergarten students who have an hour or more a night.
(Truly)
An hour of K homework a night seems quite excessive.
My kids had a homework packet in K handed out Monday due Friday. Average kids took about an hour a week to do the package. The work was broken in work for each day, but many kids just sat down and completed the whole thing on Monday. Much of it was handwriting practice. I realized that K homework was primary used for two reasons. First is to get the kids into the "habit" of doing homework. Second is it keeps the parents in the loop of their child's ability better than just sending home reports. K homework was expected to be supervised, and parents who watch/help their kids with these assignments are much more aware of their child's strengths and weaknesses.
As to homework before H.S. I think they need to have some, if only to teach the kids the study habits before grades matter so much. Teaching kids how to manage their time, keep track of homework and is a skill that doesn't come naturally to all kids. Doesn't mean they kids need to be buried in busywork.