Thanks for the suggestion, but we are not considering to change our licensing behavior. Our licenses are all fully floating, so when you start Scene Manager it will pull a license and when you exit it will give it back, that is why there is some sort of minimal communication going in the background on each startup.
Once you logged in the email and password field should never come up again (unless you start another instance of SM pararell, but again that should be also saved).
The license check or pull should take a fraction of a second and then the rest will depend on whats in the max file and how many setups you have in it.
If you feel like it is not behaving correctly, meaning, it opens up super slowly in an empty scene and/or it always asks for your credentials then please contact us at email@example.com and we can look into it.