If my users can simply install Acrobat instead of the free reader -
I wouldn't need to pay for the ability to enable a plug-in ?

Why would this be the case ?
I understand that Acrobat is a purchased application . -
But what surprises me is that with Acrobat - there is no need for a license and no cost to me (this is good)

why the difference - if I migth add -
This may just drive a decision to make Acrobat a requirement -
(I can do that - this is an internal application and we have a site license for Acrobat, etc. )