If I'm a casual computer user, who has figured out that something hinky is going on and looking for a way to figure out what's happening and if I need to pay someone to clean my system, I'm not likely to know the names of all the tools in this problem space. I wouldn't know "nmap" from "apple juice".
But if there's a repository of software which has had some basic checks done and only includes legitimate, non-pirated, malware-scanned software, and I know the repository and use it repeatedly then I can build up trust in it. If I find software which seems interesting, I can check the trusted site for it. If they provide an index, I can even check there first, for software that can solve my problems.
I mean, why use Google's Android Market, when I can just enable installing from non-market sources and install .APK files from websites I've never heard of before? Why install the Amazon market, instead of just going direct?
There is clearly a place in the software distribution ecosystem for marketplace intermediaries who can build up reputation and trust in their own right, so that end-users do not need to become subject domain experts to know who to trust as a source of software to run on their computer/phone/tablet/brain-implant/...
And just as clearly, trust can be abused and the marketplace can react accordingly to the betrayal.