Hi -- I have no problem with any of your software offering a default install location, but I do have a problem if it installs to a location without first prompting, and providing the option to change the location (most of your software does offer, but not all).
In this day and age, there is no reason to hardcode anything to the "C:" drive.
Athough AVS4YOU is not alone utilizing "C:\Program Files (x86)\Common Files", even that need not be hardcoded.