I think the issue of resurrection is more complicated in the overall story. If you look at the episode the Zeppo, obviously Jack waited time and for the stars to align, etc before he could even think about raising his zombie friends. He may be an amateur, but he did say something about how his grandfather had raised him almost right away. Also, if you look back further, in Some Assembly required, the guy is running around like a zombie trying to find his perfect mate.
Fast forward a moment to season 6 where the Scoobies are bringing Buffy back. Clearly, there are consequences which only Willow seems to be fully aware of. Did she come back wrong? Maybe a little. She certainly wasn't herself, whether it be from the fact that she was ripped out of heaven, or just brought back period.
I think the rules of resurrection are unclear. People are still doing it. Amateurs. Those who do not understand the laws of the universe (even if it is Joss' universe) find spells or other methods to bring the dead back to life, and even though the Scoobies understand the consequences, I think it's more complicated than that.
OR, maybe it's just a continuity error throughout the series, but I have a feeling that Joss had more in mind later on.
You can even take a look back further, with Prophecy Girl. The Slayer died, and was saved, but when she came back the slayer line had already changed.
Resurrection has consequences, whether it be people coming back in zombie form and trying to blow up the school, or coming back wrong. I also think that within the buffyverse mythology there are many other belief systems, and even though the basic rules apply, not everybody believes in the same consequences.
Just a few thoughts...