The publishing industry is in flux, and any new business model is going to need time to resolve problems.
I can see a conflict of interests, but as has been pointed out, the current model is rife with them anyway. One example: When you sell a book to a publisher, you get a percentage on each book sold. But who keeps track of the numbers? Who does the accounting? Why, the publisher. The less books they report, the less they owe the author. Seems like a conflict there to me.
TKA seems to be offering -- offering, not requiring -- a service to their clients. Many authors have a backlist, books no longer being printed. With an agents help, they can get the rights reverted. Then, they can self publish them as ebooks.
But not everyone is willing to go through the hassles of formatting, getting cover art, placing them, marketing, etc. The time and effort involved could be better spent in, well, in writing. And some tech challenged authors are actually incapable of doing that. Sure, you can hire an outside facilitator, but that costs money upfront and you don't know what you'll be getting.
The option of letting your agency handle it, folks you trust to do a good job, people you have a relationship with, is very tempting. 15% of your revenue seems a small price to pay.
Or, as happens to many series authors, sales slip. You've written four books in your series, and you want to continue. But your last book only sold 7000 copies and your publisher doesn't want another. Your fans do, there's just not enough of them. And future books in the series will boost backlist sales of the earlier print copies.
But sales are king. Your agent can't sell the idea to any major publisher. So again, self pubbing, where you get most of the money, seems attractive.
And your agent who may have spent years as an editor, who knows your books and your writing style, will help you get the ms into the best shape possible -- just like he or she does before submitting to editors. But no editor wants the book
So you go through the same process as usual, except the agency takes care of everything else, the way a traditional publisher would, with no money upfront, for a percentage -- the same as selling a book.
I don't think it's a bad idea at all. It may not be for everyone, but you don't have to go that route unless you want to.
And especially, if you've been with an agency for years, you develop a relationship with your agent. They aren't there to squeeze extra money out of you, they're there to help your career. And the few that aren't are going to find a way to rip you off no matter what business model is the vehicle