Hi rickp,
Root privilege is required during installation to place the binary application files in the location that conforms to the particular Linux disto's guidlines. This may be in "/opt" or it may be in "/usr/local/share/applications", "/usr/share/applications". For OSx it is in "/Applications" and for Windows it is in "C:/Program Files"
All the above locations require sudo / administrator rights. Simply, all operating systems have preferred locations for third party applications and publish specific guidelines on this. They also require that whoever is installing a third party software in the system, he or she should have root or admin rights. It is the operating systems way of determining that a competent person is installing third party software.
The QT installer system used by XyGrib adheres to all three OS guidelines as do most third party software installers. All this is intended to protect you! Not to harm you.
XyGrib provides installer packages as 95% of users are not necessarily power users and prefer a simple installer rather than dealing with compiling and building the application themselves. We are providing a free and open community service to tens of thousands of satisfied users with over a thousand downloads of weather data from our grib server every day. All this without a single complaint of evil doing as you so eloquently insinuate.
Best wishes to you,
David