Ex-Im has been around since the Roosevelt administration. It borrowed money on the good credit of the United States, , and loaned the money to foreigners to buy US built products. It returned a modest profit on each deal to the US treasury. It surely boosted exports at no cost to the taxpayer. Export mean jobs.
Granted, the main beneficiaries were big companies like Boeing and Caterpillar.
So? They are US companies, employing US union labor. All that is good. I see no reason why the US government should not support US industry. Industry creates jobs, and that deserves support.