The fact of the matter is that the Republicans started this race with 17 competitors. While I am sure all had the best intentions, candidates are often looking to further their businesses or personal agendas with their time in the spotlight. Whether it is to promote a book they have written or for name recognition, the amount of media attention a presidential campaign receives its enormous. This is why one will often see candidates without a household name.
Trump has a propaganda machine already, and should rightfully have one. His "machine" consist of himself, a director of communications, and perhaps anyone else on his team that comes up with advertising ideas. Every campaign needs to have a succinct and consistent message, delivered in an effective fashion -- whether it's through social media, print, or rally speeches.
Donald Trump's unprecedented United States presidential candidacy has actually been so successful with relatively little spending on Trump's part, and that is part of his appeal. Trump is so good at reaching his followers through his media antics that a dedicated political propaganda machine would actually take away from his brand rather than adding to it.
The question has been raised of whether or not Trump should have his own propaganda machine. The answer is simple: he shouldn't. The reason is equally simple: Trump is already his own propaganda machine! Trump is a master of spinning rhetoric to suit his own needs, the same way a hired propaganda machine would.