I'm not sure if it's BES-specific, but you can view without Docs2Go but it gets converted into mostly plain text. Docs2Go is good not just for editing, but also for presentation for viewing.
To answer your question, yes and no. You can still view the files if they are received as an attachment and you have the BB attachment service installed on your device. But you can't open the files if saved on your device without the app installed.
If you decide that you want to install the app again, use this OTA link to install it.