Endgame helped restore the Borg as very dangerous opponents. It went too far, actually. The transwarp network it revealed showed once and for all that the Borg could have effortlessly assimilated the entire Federation had it wanted to. This led to all the fan theories that the Borg farm technology by scaring opponents into developing tactics and technology that could defeat them and then assimilating it. This is perfectly logical - and scary. It suggests that the Borg could come for the Federation any time they want.
's an interesting idea. Have to admit, I'd never thought of that before.
Yeah, TOS had the Klingons and Romulans (though 60s standards meant they didn't need to meet much) and TNG had the Romulans, Ferengi and the Cardassians (though 80s and early 90s standards meant they didn't need to meet much).
And yes, it was no-win. They needed a constant foe and thanks to the audience rejecting every single last original alien they created (even when the writing was "good") they had to fall back on the Borg who were the only ones the audience liked.
"recurring" and "constant" mean different things. The Klingons and Romulans on TOS and TNG were recurring enemies. The Dominion on DS9 were a constant enemy.
And since this point has been rehashed far beyond tedium, I will simply implore you to stop being an attention whore and remind you again that writing quality is subjective and that there ARE people who don't like things that you do and that doesn't make them wrong.