A Dead Money gold bar costs 10.539 caps and weights 35 pounds. That's 301 cap per pound. For comparison, a .44 Magnum weights 6 lbs and costs 2500 caps. That's 416 caps per pound, and much easier to convert to disposable income. A Ballistic Fist's value-to-weight ratio is a whopping 1300 caps per pound. Ergo, Dead Money gold is a lousy source of caps, and one shouldn't try too hard to bring a lot of them out.
You say this as if caps per pound is a system by which anyone values anything in this game. For comparison, if the Dead Money gold bars had the same weight to value ratio as the ballistic fist (1300 caps per pound), each would would weigh 8.10lbs. With 37 bars, it'd take 300lbs of extra inventory space to be able to get the bars out of the vault without being overencumbered, i.e. if you wanted them all, you'd probably be overencumbed either way. As it takes the same amount of time to move a character overencumbered by 50lbs out of the vault as it does one overencumbered by 1500lbs, there really is no difference (except that it would be easier to leave a few behind).
Not to mention the fact that there is no other place in the game with such a high concentration of value.