Unfortunately, for Mac users zip files can be problematic. Up until Lion, unless you used a utility or manually placed files, extracting zip files to a directory in effect deleted the old contents and replaced it the contents of a zip file.... and I've done this. Luckily it setting up a new machine from a backup, so I didn't lose anything. 

Installers prevent situations like this from happening. 

I don't have issues with the installers, aside from there needs to be better options for the default installer, such as for installing a outfit. I don't need an uninstaller or an icon being installed to the desktop for content... plugins or program installs this may work for but not installing content. Also it would be nice to have batch options for installing, especially when you have a several hundred to a gig of content to install. I miss using the rendo utility for installing the daz installers, since it was nice to drop my installers in a directory and set it to run while i watched tv.

If you need to keep yourself legally protected with installers, that's fine, but the installers need to optimized so i'm not doing multiple clicks for things that don't need it. 

Also, I hope the installers will not be replaced by download managers. I had to clean up download managers and utilities that fouled up my antivirus and almost brought down my PC, so I like to keep the things I have to install and run in the background to a minimum and save those resources for my actual work. I'd suggest you look at how the earlier version of your installers work (probably from 2008-2009) and use that as a base... those were a lot simpler and cleaner to use.