Shin Muramasa
Metallic Stranger
It's easy because Metal Gear Solid: Ground Zeroes was announced sometime after?/before? Metal Gear Rising: Revengeance. Metal Gear Solid: Peace Walker was announced before?alongside? Metal Gear: Rising before it became Metal Gear Rising: Revengeance. So if Metal Gear fans do not like Rising/Peace Walker/Ground Zeroes, they can flock to other games in the series. I'm not going to comment on The Phantom Pain and Kojima's long lost, Swedish brother. Revengeance's supporters and haters I don't really know. But it seems more silently hated compared to DmC. Most of it points to Raiden's existence not the game itself.I know it's in a different world, the issue is that this is pretty much the only world we'll be getting now. I really doubt that will happen and having a good series take a backseat to an awful spin-off is not okay.
You want to know how to do a spin-off right? Look at Metal Gear Rising. While I can't vouch for the game's quality I can say that it does the spin-off thing right. It's simply a spin-off with a future and true MGS game already in the works. This image puts it nicely.
It's easy for Metal Gear fans to ignore because it doesn't disrupt the franchise.
In Devil May Cry's case, fans are left with uncertainty. The last release was Devil May Cry 4. DmC: Devil May Cry was announced like 2-4 years after DMC4. No word on Devil May Cry 5. And whether DmC gets a sequel or not, whether DMC5 is announced, whether the DMC (and DmC, because it is part of it now) franchise will exist is left in uncertainty. Of course people will be angry and anxious.