Pointless? No. Retail purchasers use E3 to get a look at upcoming releases and get an idea of what to buy for their stores (especially for that all-important Q4 period). Even if/when E3 goes the way of CES, it will still have a purpose.
As for the press? As someone who's been to E3 three times, I don't know that it's still relevant. Most of E3 reporting can be done from home; press releases, screenshots, and video footage can arm anyone with more than enough ammunition to cover E3. Perhaps there's a bit that would be lost due to lack of playables or interviews with developers, but it's not enough to necessitate press presence like we see now. There is an argument that can be made for mainstream press (Network coverage, AP/Reuters/Gannett), I guess.
That said, I think the ESA has a problem as significant publishers decide to break away from E3 proper and do their own events. If EA's event makes a fair amount of cash for the publisher, I can see more companies following suit in future years. I like the idea, personally; opening to the public brings in added revenue and builds hype. (This is why we saw the ESA go into panic mode this year by doing its own near-site event for the public.)
I'd like to see more of these separate events, spread out from April to September. Why share the spotlight with a metric fuckton of other companies when you can have your own big event?
The ESA is going to have to do some serious thinking moving forward. Should E3 proper continue to be a fairly strict trade show, with meetings and business conducted... or does it go full PAX and open to the public, forcing the hands of publishers who need hype and exposure, and thus decide to have or maintain big presence there?
I'll be very curious to see what happens next year.