There are two legitimate (and conflicting!) interests here. One is the public's right to know; the other is protection of an ongoing criminal investigation.

It's pretty clear that even if the affidavit were to be released in redacted form, Trump's supporters would focus on what's hidden behind the redactions, claiming it was some kind of 'deep state' conspiracy framing their fearless leader.

And the unredacted parts might have enough information to allow those supporters to start threatening violence - or even committing it - against any sources of information the FBI might have used to convince a magistrate judge to issue the warrant and so cripple the investigation (that I very much want to be successful).

It's clearly one of those 'damned if you do...' things. I'd like to know what's in there, too - but I'm not sure my curiosity trumps keeping a criminal investigation under wraps. I'm prepared to wait until there's a decision to indict - or not (remember this is still a possibility - it's got to be a really, really credible case that a prosecutor thinks they can win with minimal chances of an appeal).