I tend to trust myself to know when I'm downloading something from a safe source. Generally speaking as a user I wish there were more of a clear distinction between "known harmful file/website" and "Avast just hasn't ever heard of this one before." Some of us came up in an era when everything on the internet didn't come from a major app store!
All that said, it can be terribly annoying and inconvenient when Avast decides to block something and doesn't even provide a one-click option to undo it. In this regard I much prefer the choices offered by Windows or other applications ("Download Anyway", "Run Anyway" etc. - sometimes hidden behind a "See More Details" button) Moreover, when it is a clear false positive it would be nice to be able to whitelist a website (or software) without going into the app and digging through menus for it.
This was an issue I had recently with a game downloaded from the internet - after several steps of trial and error (blocked download, then quarantined installer, then quarantined installed software...), I finally got the game to install and run... but then when the patcher went to update the game a week or two later, Avast went off yet again! Turns out I hadn't whitelisted the subdomain for updates, only the primary domain. This type of thing is not uncommon for online games, for a couple of reasons: they may come from "untrusted" sources e.g. due to being a private server, and they may have anti-cheat measures that look suspect to antivirus heuristics. This can get frustrating - I just want to play my game, I don't want to dig through antivirus menus numerous times! If I didn't know better I'd almost be tempted just to go without antivirus software entirely...
When the message pops up, it would be nice to have a convenient option on the "blocked" dialog window to "ignore and continue," "whitelist," and perhaps even "report false positive" so other members of the community avoid having the same issues. I realize the latter one is riskier, but at a minimum those first two options would reduce some pretty major frustration. If you don't trust the wider community with convenient solutions... maybe leave it as a "power user" feature that can be turned on once from the menus, as opposed to having to return to the menus every other week to whitelist some new false positive?
