I am beginning to believe that the people who design webmeeting tools might be anti-social control freaks. I certainly apologize if I'm wrong, but the default settings for interaction tend to limit how people share information and interact.
Think about a traditional meeting. People can speak up, move to the front of the room to help out with the whiteboard, get access to handouts in the moment -there's a lot going on. If people want to help each other out, they can.
By setting permissions to allow meeting attendees maximum control, you not only replicate that real-life example, but can even surpass it by allowing people to print just in time and prepare their contributions to the meeting while other work gets done.
Platforms vary wildly, and some of them have all these permissions in the same place. Often the setup permissions (what it takes to log into the meeting) are designed as a separate activity to setting up the in-meeting collaboration tools.
If you're looking to get your team actively involved, learn the tools available and then take full advantage (and get your money's worth), here are some guidelines. For our purposes we won't worry about specific platforms, just functions. You can play around and discover where they are on the platform you use.
Set everyone up as a speaker or panelist. The language varies from platform to platform, but if you want people to contribute as equals, they should have equal access to the platform. You wouldn't expect people in a live meeting to sit unproductively waiting for you, why allow that in your online meetings? Allow everyone to join early, upload anything they want to present in advance of their turn.
Decide in advance what you want them to do during the meeting. Before your session even starts, you have to decide what permissions people will based on what you want to happen during the meeting. Do you want them to be able to use the file transfer? Print documents directly from the meeting or save them to their computers? And if you don't, why not?
Don't let paranoia get the best of you. In general, I tend to allow everything. First, I trust my people not to abuse the privilege (although they do have a disturbing tendency to use the drawing tools to put horns on my picture). Secondly, it's easier for me to set the meeting settings by default and leave them be. It's one less thing I have to do once the meeting starts.
The fewer participants, the more democratic you want to be about the permissions. If you have a large town-hall type meeting, you might want to limit the ability for all 200 people to write in the chat, just to maintain your sanity and maintain order. This is especially true if the topic of the meeting will be emotional. You can still allow them to send chat messages, comments or questions to the meeting leader and their assistant(s) and receive written responses, or you can address them verbally.
If you're not getting the most from your webmeeting or virtual collaboration tools, maybe it's because you're not leveraging the full capabilities. Don't let your paranoia (or those of the engineers who designed the darned thing) interfere with your team's getting their work done.