Quite frequently, logs show up things like missing files and directories, incorrect permissions, unexpected configurations etc. which can be fixed by a sufficiently technical end user, without needing to go through support.
There's a similar problem with error dialogs. Product people always push to keep technical details out of those dialogs, even if technical users would find the details useful for accomplishing their goals, figuring out what went wrong and working around it. It's more forgiveable for dialogs, as long as there are logs.
When the logs are similarly indigestible, the software is simply less usable by technical users. Quality better be damn high, because if it breaks, and there's no way to look into the hard shiny shell, it can generate an amazing amount of frustration to people who are used to making stuff work.
(Of course the % of users who are sufficiently technical is decreasing all the time.)