I've been waiting for someone to bring this up, but so far I haven't seen it explored.
Anyway, there's a very simple reason why McCain needed (from his point of view) to put out something like his "Celebrity" ad: to inoculate himself against the desperately crappy show that is going to be the Republican National Convention.
The Republicans have a legion of insoluble problems waiting for them in Minneapolis. The Ron Paul disruption. The bad symbolism of the collapsed bridge. The fact that Bush will be speaking. The fact that Cheney will be speaking. The fact that the VP is going to be lame. The platform fight. Unhappy evangelicals. And finally... the fact that John McCain has to give a major public speech using teleprompters.
Conversely, everyone knows what the Democrats have to look forward to. No third-party distractions. An energized, essentially united party. A little Clinton drama to keep things interesting, but not tear it apart. And Barack's acceptance speech in a freakin' football stadium.
The contrast is going to be absolutely enormous. So McCain had to do something; it's like he knew a flood was coming, and though he couldn't stop it, he could at least try to put up barriers to keep from getting swamped.
Hence the "Celebrity" theme. All those crowds in Berlin? That's what we're going to see in Denver, the same fervor but on American soil. All that energy? Nothing new; just more pointless hype. And so on. Spin the event in advance, given everyone a frame to see it through (including the press),
It's not going to make the Republican convention go any better, but it will help them blunt the impact of the Democratic one.
I actually think this was the main consideration behind the ads, which are otherwise pretty pointless. It's McCain's team looking ahead.
The interesting thing will be to see how much the press picks up McCain's frame in reporting the Dem convention. Do they give the Obama energy any respect, or do they dismiss it all as 'celebrity hype'? Well, I know what Fox will say, but the other networks, who knows.