When the ALM installer "installs" Client Launcher, it mainly adds the "ClientPackages" folder under webappsqcbinApps folder in the deployment area on the ALM server (usually c: programdata Micro Focus ALM)
It also puts a file called "ALMClientLauncherSetup.msi" in the Apps folder as well as a "Launcher_index.htm" file in "Qcbin" folder.
As it turns out, the only difference between allowing the installer to install Client Launcher or not is a "isLauncher Installed" flag being set and adding the ClientPackages folder.
When this flag is set to "true", the qcbin landing page (ALM/QC menu) gets little "rocketship" icons placed next to the various clients (Desktop client, Site Administrator, Lab Management).
As it turns out, the newer ALM Client Launcher 4.0, 4.1 do NOT rely on the "ClientPackages" folder as the previous 3.1 did, so it does not matter if you install Client Launcher with the ALM/QC installation or not.
Basically the only difference is whether you get the "rocket ship" icons or not (and it writes the "ClientPackages" folder)