I think it needs to be repeated that the new lighting engine
was never removed, it still has all the features they've shown and it runs on all platforms. What they did is tone down all the performance heavy aspects of it in the levels themselves, dynamic lights and shadowcasters etc. So they absolutely delivered on the promise of a new, dynamic lighting engine even if the end result is less than stellar.
Secondly,
do not get your hopes up about getting the detailed lights back through modding. The reason is that the lighting is embed in to the level and assets data, which is extremely hard for us to access without the tools FROM has. In itself it's not something that is huge thing to do with the tools, but it means that supporting the game would be near-impossible for a team the size of FROM (basically it would mean increasing the amount of possible bugs, yet almost doubling the work needed on patches).
Changing the models in the levels would also be very hard without the tools, even if the assets are still in the game files (which is actually quite likely, removing unused assets often isn't a huge priority during the last crunch). Given the quality of some areas it's also quite likely that no all of them even had a proper polish pass done or the downgrade was a really quick hack job back to the "level layout" stage of quality (basically the level is playable and complete, but is graphically missing most of the unique assets and textures and needs the final polish pass to look good).
Texture swapping is pretty much the only thing that could be done in relative ease, but for me it's definitely not the biggest factor in DS2's graphics, though better textures in some areas certainly wouldn't hurt.
Also, those spouting personal attacks such as "lazy devs" and "fuck from" should do some reading:
Working in the Games Industry: a job to die for?
These people really give their all to deliver the best game they can and sacrifice a lot for that dream. But game development is a hard mistress and a lot of shit happens, most of which we never hear about, and sometimes you just can't deliver what you hoped you would.
That said, there are problems in the industry that should be answered and these things happen because of human error as well, but that's an entirely different topic.