Yeah, I think the “appeal specialist” is the least sensible person to bring on. It’s not like you’re doing impact litigation and your ultimate goal is to make a splash at the Supreme Court. Your goal is not to die in jail. So unless there is some special aspect to your case where you think changing the law in your favor is actually a more likely outcome than just not getting convicted, it doesn’t seem like a good use of resources. Nothing wrong with having a meeting with someone like that prior to trial, though, and going over what issues you want to be sure to raise during the trial just in case.
And of course it’s a money grab for a lot of the attorneys involved, but that’s separate from the question of what benefit the defendant can get. If I am in jeopardy of life in prison and I have the option of switching out my regular, capable, Bob Mueller-style counsel for a showboat who can maybe actually sell the idea that the cops planted evidence because they’re Nazis in a closing argument, I’m cutting the check. Obviously I’m paying the best (or barring that, most unethical) experts available too. I don’t see how it can be argued that the Dream Team wasn’t effective for OJ, who, in my opinion, essentially needed to manufacture very unreasonable doubt that temporarily seemed reasonable.
Lawyers are human. They make mistakes and sometimes miss details. Which is why wealthy defendants hire a team of lawyers; so one lawyer doesn’t have to be responsible for everything.
As you and other people have noted, you want to have a lawyer who is completely focused on running the current trial. This lawyer’s focus should be on winning this trial and thereby eliminating the need for an appeal.
At the same time, you want to somebody working on the back-up plan in case you lose this trial. Just as you want one lawyer to have his undivided attention on winning the current trial, you want a different lawyer to have his undivided attention on preparing for the appeal.
For what it’s worth, if I had infinite money, I wouldn’t see a problem with hiring an issue spotter to preserve for appeal issues that my trial counsel might otherwise have missed. And I might want someone who might be able to focus on tangential issues like interlocutory appeals that might otherwise distract my trial counsel. Having more people who remember the trial record and can identify inconsistencies in testimony for cross examination would also seem helpful. Yes, my trial counsel should do that. But the more people focused on these issues, the merrier.
And, having just Googled a bit about the case, it seems there was at least one at least one interlocutory appeal during the trial. Perhaps Dershowitz was money well spent. Simpson certainly can’t argue with the result.