If you insert a link in the WYSIWYG-Editor, it will be formatted. That is better in the current official TinyMCE-Rich-Text-Editor.
See this video for a demonstration:
Paste as plaintext button would be nice. All that is needed is pastetext in theme_advanced_buttons1 property in TINYMCEPLUGIN_INIT.
These sorts of issues could be left to user/admin prefs if we can accommodate toolbar customisation in to my feature proposal at TinyMCEPluginShouldBeMoreModular.
Changing this to priority: enhancement, because we already have a "remove formatting" button. If you feel this is more urgent than enhancement priority, help me get the feature proposal moving (because I don't think we should clutter the toolbar any more than it already is)
-- PaulHarvey - 21 Oct 2009