Why can a dermal patch for drugs like nicotine or fentanyl work but other drugs cannot pass the dermal barrier?

What specifically about the pharmacology and dose delivery of these drugs make dermal patch delivery successful but it's rarely used as a delivery vector for other drugs? The method of delivering other drugs (like vaccines) transdermally had been experimented with, but why in 2011 is this medical technology still relegated to old Star Trek reruns?