Romain Dillet at TechCrunch explains it like this:

Now when you land on a company profile page, you will see a big brand name with a small @username below, a gigantic header photo, a small logo next to every tweet, photos of new products in the sidebar without having to scroll, a pinned tweet at the top of the timeline for a current promotion, and finally the traditional flow of tweets.

Twitter is not hiding the ball on this one: their advertising blog post makes it hard to see the new profiles as motivated by anything but improving advertiser utility.

Twitter’s downward spiral into user-neutral (at best) and user-hostile (at worst) changes suggests their ignorance of the operating principle I mentioned last week.

That’s a shame, because the company-first-via-users-first approach is serving Amazon and Apple, and their partners and users, very well.