1) There is already balkanization based on countries. Does California change that situation so much? Enough that it shouldn't perform it's role in the U.S. as a laboratory for legislation (a role of all states)?
2) Commerce and communication restrictions should not be considered without also considering the purpose and benefit the legislation intends to cause. First and foremost is whether it actually helps more than it harms. For example, it could have been (and I'm sure was) argued that abolishing slavery was problematic from the standpoint of groups of people and businesses interacting with those states and what it meant to use slaves in them or take slaves to them. The point is not to equate this issue with the abolitionist movement, but to point out that how the law affects interactions between states may have very little (or very great) bearing on whether it should be ratified, and it depends entirely on the legislation in question. Great leaps in both positive and negative directions both cause friction between (nation)states, so friction itself is a poor indicator of whether legislation is good or bad.
2) Commerce and communication restrictions should not be considered without also considering the purpose and benefit the legislation intends to cause. First and foremost is whether it actually helps more than it harms. For example, it could have been (and I'm sure was) argued that abolishing slavery was problematic from the standpoint of groups of people and businesses interacting with those states and what it meant to use slaves in them or take slaves to them. The point is not to equate this issue with the abolitionist movement, but to point out that how the law affects interactions between states may have very little (or very great) bearing on whether it should be ratified, and it depends entirely on the legislation in question. Great leaps in both positive and negative directions both cause friction between (nation)states, so friction itself is a poor indicator of whether legislation is good or bad.