The NK government permits and actively encourages foreign tourism for the cold hard foreign currency, external & internal propaganda benefits, and use of hostage-taking, because it calculates that the benefits of those outweigh any drawbacks of a closely-watched tourist being escorted along beaten paths from propaganda site to propaganda site. An inexperienced non-native foreign tourist visiting for non-tourist reasons presumably believes the opposite. Who is more likely to be correct?

'Getting experience in North Korea' is perhaps one of the worst things you can do if you want to work as a diplomat (or in government more broadly).

Taking US diplomats in particular (although this generalises well to other government roles, and to other countries) people in these roles - ditto ~half the federal government - require a security clearance. Going on your own initiative to a hostile foreign power (circumventing state department attempts to prevent US citizens going without their express dispensation due to safety concerns whilst you are at it) concisely demonstrates you are a giant security risk.

This impression gets little better (and plausibly even worse) if the explanation you offer for your visit is a (probably misguided) attempt to conduct tacit economic warfare against the NK government.

Uh, sorry but how is this even a question? Is visiting South Korea "effective"? Is visiting Nigeria "effective"? Of course not, they're vacations. What exactly would you do in North Korea... smuggle USBs and tell them about freedom and mukbangs??

it seems possible that more Western visits to North Korea would strain the resources of the Kim regime.

1. I imagine you'll be paying them 2. Is this supposed to be a good thing?

Experience in North Korea would probably also build one's career capital (by boosting reputation, signaling risk tolerance, and (perhaps) establishing relationships in the DPRK & China). This seems especially salient for folks who are aiming at diplomatic & public policy careers.

No one is going to get hired for taking a trip to a foreign country, that's something you put on a freshman college application not a resume in the real world. You don't get a reputation for taking a vacation, except maybe a bad one if you brag about taking a sightseeing trip to a dangerous country against the advice of the actual State Department. No one needs "risk tolerant" policymakers, what risks do you think policymakers have to deal with?

What exactly does China have to do with DPRK? Is DPRK somehow crawling with Chinese officials that you are going to befriend on the street??? And what are you even going to do with a relationship, "hey man I really hope you stop your nuclear weapons program" ???

See also this Quora answer about visiting North Korea, which gives interesting context.