I should add two important notes:
1. Using the Remote Script Editor, you can File -> Load the script into place. Loading in the script editor does not immediately execute the script, so you can already preview a script in this manner-- if you don't like the contents, unload. If you do, you don't have to do anything.
2. For those technical enough to even understand what is in a script, using notepad to view the file and then /load or File -> Load in the script editor to load the script is not such a leap. For those not technical enough, previewing won't make a difference. Making a "newbie friendly" UI for previewing scripts won't really benefit the right people.
