How can you design anything if you don’t understand the strategy behind it? And how can you design anything intelligently if you just take forward strategy unquestioningly, without getting the process and logic behind it. So insist on being part of the process upfront. Be part of the research, contribute to the positioning discussions, understand why a particular strategy is a good choice. It’s not rocket science. And just the fact that it annoys you to be left out of the process, is a sign that you are willing to invest the extra time and effort needed for this. I think you’ll also find that if you are part of the project from the beginning, not only will you deliver a better design solution, you will find it easier to connvince the client to take it.