I've skipped over some of the discussion but it should be obvious (if only after someone more neutral points it out,)
but modern Klingons are unbelievable.
There is no convincing way to rationalize the continued existence, much less progress of such a society. Obviously that's because the modern Klingons are not really thought through, not really written. They are melodramatic poses, struck for coolness.
Real people are inseparable from their culture. The same is true of fictional people, even fictional alien people found in SF. A good deal of the problem is that so many writers find it profitable to accept the capitalist ideal of economic man, a socially atomized creature who is uniquely responsible for his fate. This is a convenient ideology for the rulers, as it denies that social problems even exist, meaning that there are no social/political solutions, especially those that treat the economy as a human creation, rather than the natural (or God-given) order. Unfortunately for the artistic pretensions of such writers and dramatists, their beloved view of the Human Condition is ignorant lies.
Modern Klingons are stupid. The original Klingons were the nefarious enemy. Star Trek portrayed "us" as making peace even with enemies in Errand of Mercy, Day of the Dove and even Trials and Tribbleations. A Private Little War was a partial exception, but the phoniness of the comparison to Vietnam was a dead giveaway. Powerful Klingons who get their power from nowhere are ideological constructs, fake enemies for vicarious hate-ons against the latest designated threat to our lives. Any ambiguity about Modern Klingons lies in a yearning to revel in the fruits of empire.