Hi Vadim,
Everyone I’ve talked to tends to agree that conforming to MS best practices and supporting per user installs is a theoretical ideal for many cases. However, my contacts also point out that many complex, enterprise-class products do neither. The Acrobat installer engineering team takes utmost precautions to comply with all basic principles. Installer features in A11 were designed to prioritize core principles and standards. The team always refrains from writing custom code when possible.
In fact, even Microsoft fails to adhere to their own best practices. Here is the link for MS office 2013 help page http://technet.microsoft.com/en-us/library/cc179018.aspx , search for the text “All installations of Office 2013, Office 2010, and Office 2007 are per-computer.” Further research shows that Office 2010 and 2007 also do not support per user installations.
That fact that Acrobat only supports machine-level installs reflects product and feature constraints rather than a lack of interest following MS’s best practices (which are generic recommendations). On the other hand, your excellent post raises the question of whether Reader needs to be treated same as Acrobat. The team is looking at this issue.
You are also correct that icon paths should not be hard coded. A bug has been filed.
In an effort to help those of you who need per user-like installs, the Acrobat team is investing heavily in App-V and other virtualization techniques. Possibly not exactly what you want, but that’s where the market seems to be heading these days.