Yep imagine them showing Version 1 Black Widow that would be like Chun face debacle all over again lolWell, if they showed a trailer with fully functioning characters, people would accuse them of 'withholding finished content'.
If they simply said nothing, people would complain about "having to buy a season pass without knowing what's in it."
Also, the characters may legit not be finished. Whenever Capcom shows something that's still a work in progress, people don't take it very well.
This is probably the safest way.