Nothing turns you off more from a conferencing solution than: any problem getting it working right now.
When there is just the slightest issue, one person not being able to join, one person not getting voice to work, bad audio, your entire team is blocked/distracted. Which results in a collective distain for the solution and video conferencing as a whole.
This extends to getting the solution working for greenfield installs as simple as possible. Because who knows which non-tech users from which department all need to join and can't figure out how to set the permission in their browser right or install/use the other browser that is compatible.
So sadly, from a functionality point of view, you want have the software be able to force itself onto the user in the most usable state it can.