I'd agree that only the first 2 benefits are significant. The third is granted to all customers anyway, though the writer of the article is incorrect to dismiss it, since customers do claim successfully on the occasions when the prices drop. The dedicated contact centre might be useful, I wouldn't know as I can't remember the last time I called them.
All that said, the fee-free changes would have saved me a few quid this year, so I'd be happy to be a member for this alone. On the basis of the anticipated criteria, I'm borderline having flown 20 sectors on U2 this year, will depend when they measure it.
Enough to make me book more sectors? Maybe, maybe not, but it's certainly not going to make me reduce them. In my case the thing that did the most to tip me towards shifting a chunk of shorter flights away from BA was the allowance of a second piece of hand luggage to U2+ customers, and price didn't hurt either.
There is nothing to stop them adjusting the benefits over time to assist loyalty. A discount on U2+ renewal would be nice...