I'd take that one step further, and say that players very much DO need to be able to create content. The existing Player Edition is very much a passive experience. But an RPG isn't just listening to a story the GM tells. It's a much more collaborative experience, with input from everyone at the table. And so should be tools like Realm Works.
The most obvious content they create is of course their characters. There's no reason they can't show up in the database. But why make the GM into their secretary, transcribing all the player-generated material into the database, especially with all the other work the GM has to do? The players can just do it themselves. Also note that it's common for player characters to have secrets, just like NPCs. Players should be able to reveal snippets of items they "own", just like the GM does.
Some players get even more into it, and create complex backstories for their characters, which might involve past histories (plots), people, organizations, and plot hooks. This is all good stuff to have in the game database, especially as the GM weaves those people and hooks into his own plots to integrate the character into the world.
During play, players need to "take notes" that are about as elaborate as the GM's, not just text boxes. (I've got Notepad for that...) They encounter people, learn things or think they know things, and have their own view of the world. The players should be able to collaborate on their view of the universe, and build a structure. The GM's version is of course The Truth, but that doesn't mean the player version isn't important or shouldn't be allowed to exist. Player versions might be modeled with "secret identity" type relationships to link to the true GM version; or perhaps the distinction can be handled simply by ownership tags on snippets attached to a single object.
Then there's the scenario of co-GMs, who both share items and have secrets from each other (when they play in each others' games). This is a little more complicated than the one-GM setup. With one GM, you could assume whomever is marked as the "GM" has access rights to all the "player" topics. With co-GMs, that data structure has to admit overlapping sets of items, not just a strict hierarchy. This data structure also lets you have topics owned by a specific player (like their character) and topics that are owned by the players in common (like their campaign log, theories about important NPCs, and so on).
The Player Edition is a nice idea to help get people involved with using the tool at lower cost. But I suspect it's not worth the development effort. The upcoming web viewer will be just as good for the passive presentation use. Realm Works itself could revert to a single mode of operation, but with a richer notion of ownership of items and "reveal rights".
In practice, I found the Player Edition too limited to be worth using. Regular software like OneNote was better for just taking notes; mind-mapping software or drawing tools if I really wanted links and plot diagrams. The GM Edition of Realm Works is better yet than most of those things at creating a rich description of the game -- but the full functionality needs to be available to players, not just the GM, so that the players also have a rich experience.
