1. It is impossible to delete this text template in case you want to save an item with an empty text field. You delete the prepopulated text, then save: the text keeps coming back. Even worse: when you click «Save & Close» you will most probably not realize, that the prepopulated text has been published. In my opinion, the text template should be inserted once, when creating a new article.

It is not possible for JCE to know when the article is new, only that the article content is empty. It is possible to determine whether the Joomla Article Manager article is new, ie: it does not yet have an assigned id, but this doesn't work for other components, that may use a different syntax for the id or have some other kind of save routine that makes retrieving the article state difficult.

2. JCE Editor is prepopulating any text field that can be found. Let's assume we create a new category, but we do not want a category description. The text template is being inserted in the category description field, although this does not make sense at all. Another example: we use Visforms. Here we have a custom text field that can optionally be added to any form field. Under no circumstances we want the text template being inserted here. But this is exactly what JCE editor does. After having created a new form with Visforms, the form is completely spoiled with senseless text between any form field.

This is the point of editor profiles. If you only want the Joomla Article Manager content to be prepopulated, then create a profile assigned only to the Article Manager that contains the Startup Content option.