Currently there is no way to prevent quoted text from being line wrapped in replied messages, except of disabling global smart quote setting.
On developer mailing lists for instance you want quoted text not to be wrapped at all (as it might contain code diff), whereas own text inserted in between the quoted text lines should indeed be line wrapped OTOH.
As a first step to support this use case, add a checkbox "Wrap" to the template configuration dialogs. By default this new boolean setting is on. If this template setting is explicitly disabled, then quoted text will not be line wrapped e.g. when replying to a message, and the "Wordwrap" option in the composer can still independently be used.
Known limitation: if the "Wordwrap" option is enabled in the composer, then the quoted text is unfortunately also wrapped subsequently, so currently a user would need to disable this option in the composer and manually wrap own text if required. Unfortunately this is not easy to solve as the "Wordwrap" option's behaviour is implemented by QRichtTextEdit and apparently cannot be overridden without Qt source changes.