The Person that is to install and operate LoadRunner needs to be the local administrator or a Domain Admin that HAS full local administrator privileges.

LoadRunner components will perform read/write actions on the main Windows directory and System Registries.

Please remember that LoadRunner is an extremely powerful application with the ability to record and monitor the performance and communication between applications, including the Operating Systems itself.
Due to security issues, it is not desirable for big or small size companies to have an application that is capable of:

1) Spying on other applications (VuGen recording), and it act like a key logger

2) Pretending to be other applications (Load Generator), and

3) Gathering information about remote systems (Controller monitors)

...without even having admin permissions. Most company don't want the users and employees to do this without proper permissions. So why would a company want testing tools that could do those things WITHOUT ''admin permissions''?

This explains the reasons as to why there is such a requirement.