Why are most mass media populated Only by people I dislike and despise: and nobody-at-all with whom I wish to empathize?

For me, much of the mass media output is ruined and made intolerable because populated entirely by dislikeable characters. 

Indeed "dislikeable" is putting it mildly! Most media dramatis personae (whether in TV, movies, songs, plays or novels) are people I regard as actively loathsome individuals!

I used to theorize this on the basis that it was part of the strategy of corruption; for instance that heroes were - over the past decades - replaced by anti-heroes, and virtuous exemplars were replaced by "victims". This is surely correct - so far as it goes...

But I now think the proximate reason may be simpler: 

That the authors of TV, movies, songs, plays and novels are writing about what they know - and they know evil from the inside and by-experience; and know almost nothing of heroism, virtue of Goodness. 

The authors and artists themselves typically lack such virtues to begin with; and to make matters worse have strategically affiliated themselves firmly to the devil's agenda.

I mean, they authors have embraced the anti-God, anti-creation, anti-Good agenda that is pursued by "the global establishment", top-down; and via all possible means...

From direct coercive power (laws and regulations), through subsidy and awards; to multi-pronged ideological propaganda that naturally (and very importantly) includes "the arts". 

Furthermore, the mass media world they have chosen to inhabit and in which they participate is pervasively corrupt: the world of movies and television, directors and actors, publishers and marketing, patrons and "arts administrators", reviews and critics, musicians and production...   

In conclusion; there are (by my judgement) no virtuous characters in the great bulk of mass media, simply because those who produce the mass media are themselves deficient in virtue and live-out their lives among some of the most corrupt and value-inverted human beings the world has ever known. 

And, what is worse, authors depend on the good opinion of these corrupted persons; insofar as the authors desire money, fame and high status. 

With authors being as-they-are and working in the environment they actually do; it is to-be-expected that the modern mass media is replete with actively-evil protagonists (liars, cheats, selfish hedonists, psychopaths); while the truly virtuous are depicted unconvincingly - or most-often not-at-all. 

And when there is any attempt to depict genuine virtue; because authors personally know nothing of such matters; these characters inevitably will be pathetic, miserable, simple-minded, deluded - but inevitably victims. 

It's not that authors are merely representative of the corruptions of this era - things are much worse than that! It is that authors are among the avant garde of evil: they personally are active advocates of, not merely going-along-with, the agenda of evil; and that authors inhabit a social-world of like-minded persons - the society of those who have chosen, professionally, to join the primary servants and implementers of the demonic strategy.