You apparently missed the $hit$torm that was the MGR boards when the game was first announced. Oh yes, there was plenty of hatred and hell to be found there. However, pretty much all of that died off when they announced the next MGS game and people finally came to grips with MGR being a separate entity. Again: Capcom has stated the future of DMC rides upon the sales of DmC - for good or bad. Do we know what those sales mean? No, but it's understandable that people are more upset about this than a game which doesn't affect the main series.
TAKE THE HINT CAPCOM!! ANNOUNCE DMC5!!!!!!!!
I'd say this is probably pretty accurate. If DmC was a spin off or its sales didn't decide if DMC 5 will be made, I think people wouldn't be so up in arms. With MGR, more can be forgiven. Since Ground Zeroes has already been announced, MGR is a spin off series that doesn't affect MGS (at least gameplay wise, story wise, who knows), and MGS 5 has been teased (read: Phantom Pain). Also, DmC's story comes across as edgy and over the top. MGR is probably going to be over the top too, but in a more Kojima-esque convoluted fashion.
I'm not looking to start a war, but I'm just saying why MGR can be more forgiven then DmC.
"Modern Biology is Chemistry, modern Chemistry is Physics, and modern Physics is...crazy." - Mark Peyron