It reveals dependencies. People might be concerned if, e.g., 90% of government spending was valid if and only if the commerce clause had a particular interpretation.
Companies disclose if a single customer represents even 10% of their revenues, because it's a risk factor.
Looking at that would be a great way to create some really perverse incentives.
"Let's spend more money on the armed forces and post office, to make the portion that comes under Clause 3 appear smaller."
A lawyer I spoke to told me that there's a question regarding federal law on the bar exam every single year, asking "From where is the power to create X law derived in the Constitution?" It's a different law every year, but the answer is always the same: "The commerce clause."
Companies disclose if a single customer represents even 10% of their revenues, because it's a risk factor.