(1) normal use: I like to switch between presets without any parameters frozen.  I can do that if I follow your suggestion, or if I manually untick the box every session, but ...
(2) occasional use: when I explore a preset I haven't tried before (for example a downloaded .fxp) I like to start by freezing some parameters which suit my keyboard and speakers (for example velocity response, mic positions and reverb). If I follow your suggestion I have to redefine that set of parameters each time that I want to use them.

It would therefore suit me if Pianoteq opened with the freeze parameter box unticked.  For normal use I would not have to untick it every session, and for occasional use I could tick it and then my default set of frozen parameters would be activated (I think).