The Quick Reply system was developed to be a "No Frills" reply box, that doesn't use any type of additional JavaScript which could slow the page loading time. If your users want smilies they should use the Full Reply page; if the Quick Reply feature is causing some confusion you could disable it in the Control Panel and when they click the "Reply" button they'll be brought to the full editor.
Now, nothing would be stopping you from modifying your forums, or hiring a 3rd party developer to make any feature you'd like, to be run on your forums.
