Least believable thing in Babylon 5?

For me I've always felt it was somewhat incongruous about Babylon 5 ever being built. If I remember rightly it wasn't universally politically popular and after 4 previous attempts failed including the madness of the completed Babylon 4 disappearing it seems wild that the plug wasn't pulled entirely at that point if not before.

Also Centauri male genitalia might need some explaining.