There is nothing wrong with day one (or on disc) DLC.
Every game has a set budget, set timetable, set man power. All day one DLC is not simply content cut from the main game, and to just assume that is too cynical in my opinion. Most DLC is probably made outside of a game's original budget, with the intention of being able to make it's money back by being sold separately from the main game. Certainly there are instances of developers/publishers cutting content out of a game to make an extra, but I see no reason to assume that is the norm beyond typical online cynicism. If the publisher offers a developer more money, on the condition that they use it to make DLC content, I hope the developer always says yes to that.
I mean, look at Destiny: yes, it was possible to access DLC areas on the disc, but these areas were by no means finished, and wouldn't have even been there were DLC not a thing.
Than there's MKX. This is game being made for next gen consoles, so right away the cost for making anything in it compared past games is considerably higher. Than you've got the longest story mode in MK history. Comparing this roster directly to the last game, it's 24 characters now vs 27 characters in the 2011 version (comparing the current roster to older entries in the franchise is comparing apples to oranges, because the cost of making games has gone up considerably due to higher fidelity graphics and more costly production values). Each of those 24 characters have three variants, however. Essentially, three different fighting styles using the game character model. So in reality you've got 72 different fighting styles to work with.
I don't even intend to buy this game, but this kind of cynicism towards DLC has really started to bug me. Just be happy the content is available. It used to be, once you beat a game, that's it. Now games can continue to be supported with new content for years after the fact, without having to wait for a sequel to fix the problems, add characters, or continue the story. I think that's pretty neat.