I really like the constitution with the tenth for the diversity it allows, as well as the way it builds to good laws for contentious issues over long periods. It’s great that states can legalize gay marriage if they like the idea, and it’s also great that there are different formulas cooking in several states for civil unions. We have fifty legislative laboratories and over time they arrive at things that make sense and work. Eventually the things that work get copied, and then moved to federal level. That aspect of the tenth is wonderful.
Some consider the tenth superfluous, as it restates some of what’s said earlier, but I think it does need to be explicit.