As far as the first study goes, I don't see why we should control for income and marital status. If EQ increases income in a way that increases life satisfaction then EQ is a highly useful construct.

That said there are political problems with treating openness as a variable to be maximized. Openness correlates with voting left in US elections. Teaching people to increase their abilities of emotional management might be politically easier to communicate.

A lot of personality tests are also easy to game if a person wants to score highly. The notion of intelligence supposes that getting high values in the test needs actual skill.