Yes, it was and it was intended since the book, published in 1968, to be just that. It is an anti-war program and having been in one, (a war) it is needed to inform those that haven't just how freaking awful war is, albeit shown in a more palatable way! What they managed to do was to expose just enough personal upset with absolute human waste of life. Sorry, if hearing about it offends anyone, however, living it was and still is far worse. If "preachy" means being shown the crap that humans are constantly seemingly programed to institute, then it is used properly.