That said, by and large, people seem to like the DC shows (Supergirl and the Flash in particular). This, however, looks like a misfire. A dreary misfire. No one says that their favourite thing about the Teen Titans is how unfun they are.
I have tried three of those shows that people love and... people are wrong.
I agree. Arrow and Gotham are particularly unwatchable for me (the others to a lesser degree).
I think it is partly because the DC TV (and film) is like DC comics: they are plot-driven, not character-driven. Marvel (both comics and TV/film) are character-driven, with plots present, but what is going on with the characters internally and in their lives at the forefront. I don't care for plot-driven, because I am interested in people, not 'events' per se.
There have actually been two DC shows I enjoyed. Both were cancelled. The two were Human Target, and Constantine (though I've only seen the latter once - not yet re-watched). I am, as yet, unsure whether I will continue watching Black Lightning. It is, of the current DC shows, the one that is most interesting to me, as the characters themselves are important.
Of course, it could also be the DC/Marvel 'dark'/lighthearted aspect that is at issue with the shows and films. It seems that since 'Watchmen' and 'The Dark Knight Returns' were originally published, DC seems to think that success can only come from 'dark and gritty'... which makes them often unreadable/unwatchable (as this looks). Human Target and Constantine also had more 'genuine' humor in them than the current Supergirl/Flash/Arrow/Legends/Gotham batch.