First, I assume the estimates on capital flight in the WSJ are based on Pichet's 2007 paper, which makes a number of huge assumptions to arrive at its estimate. This isn't necessarily a criticism, more a statement that there isn't a lot of good evidence and other approaches to estimation yield much more modest sums.
Second, the article does not say that "the wealth taxes generated less revenue than the ordinary income taxes would have." It says that "the government was losing revenue from income taxes that the wealthy would have paid." There isn't a comparison there. Sure, the government was losing some revenue from income taxes, but nothing on the order of magnitude of the revenue brought in by the ISF. Those who are extremely wealthy actually do not tend to pay much in income taxes, especially outside of the US where top salaries are significantly lower.
Third, the assertion of widespread capital flight in France is provably false. If we look at French national accounts, the larger a fortune (and therefore the greater percentage of which is made up of financial assets), the more it grew relative to smaller estates (which are predominantly composed of property). Under the hypothesis of capital flight, we'd expect to see exactly the opposite.
Fourth, the effectiveness of the wealth tax had nothing to do with its repeal - it had to do, in large part, with the specific politics of the internationalist-global coalition that Macron spearheaded.
Fifth, even if capital flight becomes an important concern (and I do believe it is important, simply not at the level that is often cited), there are plenty of ways it can be circumvented, especially given the very different dynamics of the US tax system and the US place in the world.