The view presented before the last line is counterproductive on so many levels. There's a nice name for it: http://en.wiktionary.org/wiki/defeatism Acceptance of defeat without struggle.

The problem with the writing style where only the last line brings the change in mood is that a lot of people don't read everything.

The direct call to action is always a better approach.

Don't make the text full with wrong arguments and end it with "but." Just write the good arguments.