There's a difference between ebooks and self publishing. Publishers are taking full advantage of the new technology. Even Amazon has its own traditional imprint now. If self publishing was taking over and publishers were losing out, Amazon in no way would be investing in paying for such quality editors to come on board, or such high advances to its authors.
Further, of course you're likely to have self published books dwarf traditionally published books. There are more authors who couldn't get publishers than those that could. Everyone who was ever rejected now just puts their stuff out there. Because of course it wasn't rejected because it was bad, it was rejected because publishers are idiots /sarcasm. (okay, that's me being very mean - I am well aware publishers are far from perfect - two of the best books I've read recently have been treated horribly by publishers. One had the rights reverted recently, the other couldn't find any kind of home until a small press took it on. My point is simply I am really sad that many writers these days don't take the time to evaluate their own work and see if maybe there was a reason it was rejected, and work to improve it, as opposed to just assuming it's perfect and posting it online).
Now, that's absolutely not saying that there aren't best selling self published authors out there, and that self publishing isn't a viable alternative for some authors. A viable alternative even for me maybe, I'm definitely thinking about it for one of my books which suits the ebook format I think. But the numbers don't always say what some with a vested interest think they are saying.
Witness the interview interviewing a one Mr. Konrath. That's all the evidence I need of a biased article. Oh, also Mr. Konrath signed a publishing deal with Amazon, so clearly he doesn't feel that self publishing - despite all his success - is the only way to go. No matter what he insists elsewhere.
I should also point out that when someone is hugely successful, or even decently successful with a self published work, the news is spread like wildfire. By the industry, but also by all those hopefuls who want to use the news as validation that they too will be that successful when they self publish. The fact is, you still have traditionally published authors doing just fine, but that isn't news. And it's fairly common in fact. Because success in self publishing is so new and rare, you hear about it more. Giving the impression that publishers are suffering horribly.
Now I'm not saying that things aren't changing. And I will admit to getting frustrated with some publishers for not being more forward thinking. Especially with regards to ebook royalty rates and pricing. But things aren't always how they seem.
I guess for me what it comes down to is an article that is all speculation. And interviews with people clearly invested in the self publishing niche. Though I will admit this is a more balanced article than most, you still notice not one of the Big Six was interviewed.
Anyway . . . all this is in response to your posting this article link.
To answer your actual question:
I chose traditional because I wanted to focus on being a writer first. I wanted to work with a team, an editor, a marketing department, a design team. I wanted people who were good at their jobs helping me make the best book I could. And all for free. Further, I actually got paid to write. AND my book will exist as a physical book. And say what you will about ereaders (I do love my Kobo), there's nothing quite like a real live book.