It was kinda hilarious when the Republicans attempted soul searching after the Romney election and pretty much concluded that they couldn't.
Their bullshit line of that week (I think it was hammering on Obama's "You didn't built that" line) just didn't work.
"Make America Great Again" was a stroke of genius, much like "Get Brexit Done". You can pretty much fill in for yourself what 'Great' or getting 'it Done' entails.
"Keep America Great" in that regard is a terrible line. Because you assume that the audience already thinks "things are great" and they likely don't feel that way and it doesn't create a desire or urgency to get into action.
In fact, I believe Hillary used the "America is already great" line often as well as "Stronger Together", which again is a terrible slogan because anyone who has ever done a group assignment knows that not everyone is making you stronger.
Sometimes you feel you're better off doing things on your own.
Same with Corbyn's "For the many not the few". Most people consider themselves exceptional and would more likely consider themselves to be the "few geniuses" that wanted to remain vs. "the many" that wanted to leave.
