On-disc DLC tends to ruffle feathers, making gamers feel like they're forced to shell out more money for content they've already bought. The dust was most recently kicked up in the case of Street Fighter X Tekken, when it was revealed that the large roster update coming to Vita much later in the year is already on-disc in the console versions, ready to be purchased for 20 bucks when Capcom flips the switch.
This led some fans to the Better Business Bureau, and Cinema Blend reports that Capcom has now issued an official response to the complaints.
SFxT has an enormous amount of content, fully developed and available for play and enjoyment immediately on-disc. Given the 38 characters available for full play, as well as multiple play modes, SFxT provides great value for all players from day one. While Capcom is sorry that some of its fans are not happy about the chosen method of delivery for the DLC, we believe that this method will provide more flexible and efficient gameplay throughout the game's lifecycle. There is effectively no distinction between the DLC being "locked" behind the disc and available for unlocking at a later date, or being available through a full download at a later date, other than delivery mechanism.
In terms of legal realities and business planning, Capcom is probably right. DLC is built in such a way that it usually wouldn't be made in the first place if the business plan didn't count on making more money from it, on the disc or not. And thanks to how digital rights law works, you're really not purchasing ownership of everything on the disc anyway.
However, the problem with on-disc DLC is largely about fan perception and good PR, so this justification is likely to only add fuel to the fire. Plus, for a company that's grown infamous for reviving its Super and Hyper editions lately, having a large roster update ready to roll out on day one may feel like a back door to the same end.