Secret characters is just something that we lose as a whole, not only in Smash. I remember for Mario Kart 8 when the Koopalings had a trailer... We get unlockables instead of secrets now.
And while I grew up with "getting games without knowing much about it" (oh boy, the day I unlocked Mewtwo in Melee!) revealing the entire cast of characters just make sense with the social media era.
For the direct, Ashley and Isabelle would be the perfect scenario for me. While I obviously would like her as a unique fighter, Isabelle just make sense as an echo to me.