I mean, it’s not necessarily a better deal. Disney can continue to adjust their platform in attempts to prevent piracy, but anyone can rip a disc without any coding/hacking know-how or VPN capabilities. So, while those with the ability to rip from D+ may have “the better deal”, far less people are able to pirate and just end up subscribing.
Also, there’s more and more technology going out with tracking digital screeners (for awards season), where they can lay in video information specific to each person accessing the file to track down anyone who pirated it, without showing up to human eyes (though staying present in transcodes). It’s not likely robust enough for all of Disney+‘s subscribers just yet, but in a couple years it likely will be.