I suspect she actually is, in a weird way.
Historically? There's absolutely no comparison. Diana is a legit franchise Alpha around whom an entire mythos is built, while Harleen Quinzel is ... definitely not that.
But lately? I can't shake the feeling that Harley Quinn is somehow more DC's "It" Girl than Diana is. Seems like, while she doesn't really carry a solo franchise, Harley is everywhere or inserted into anything.
It's the exact kind of concerted push that I thought for sure we'd see with Diana after her 2017 blockbuster movie ... only that never materialized.
I know DC totally sucks at marketing synergy in general, but I don't get why Harley Quinn (who committed or aided/abetted countless felonies including 1st-degree murder) gets this corporate love from DC/WB while Diana just gets paltry stuff.
Maybe it's just the optics are bad. Maybe there's no disconnect.
I think there is. Do you?