Fidelity to the source material is one of those things that isn't always necessarily a steadfast rule. As was mentioned, Guardians takes a LOT of liberties with the source material and even certain characterizations, but it gets the core elements right and is an enjoyable movie in its own right. There's a number of things the Tim Burton Batman movies get utterly wrong as adaptations, but they're still able to stand on their own as well made action films. There are also many comic fans who flatout hate the Fox X-Men movies for all the changes made to the comics, but they (the good ones) were still able to connect with a mainstream audience.
The problem is when you make changes to the source material that also actively harm the movie. Fan4tastic pissed everyone off by making Johnny black and having Doom be a Cheetoh-munching gamer nerd, but it was also just a terribly written and directed movie in its own right that also obviously had huge chunks that were edited or reshot after the fact.
GITS falls into that latter category, I'd say. In trying to simplify or downplay the weightier themes of the original, it made itself very boring and run of the mill in the process. That's why the general consensus among most of the reviews is "It's okay, but it's also boring and not anything we haven't already seen a billion times in better movies."
And of course it also happens that they made one specific change that caused a bunch of negative buzz and controversy, and as VileOne said, never found a good way to address or get out in front of it.
Did it? Because it was quite a bit of time between Evolution and Battle of the Gods. I mean, even Godzilla 2000 came out a year after Godzilla 98.
In a making-of book, Toriyama mentioned that he got so angry after seeing Evolution that it inspired him to write a screenplay for a new animated DBZ movie. That was the project that eventually evolved into Battle of the Gods.