The <html:text> tag requires quotes around the value property you specify regardless of whether it's a scriptlet or not. It does accept scriptlets, but requires "all or nothing", meaning the entire value must be a scriptlet, or none of it must be a scriptlet. So, the following should work:
One additional note: The only reason for using the <htm:text> tag as opposed to an <input type="text"> tag is that it already populates the value for you based on the property of the ActionForm bean you specify. If you're overriding this value anyway, there's no real reason to use the <html:text> tag. The following will work just as well.