Well that’s mostly due to the Church and the Popes perception of events, and American consumerism of their multiculturalism.
There are several interpretations, but generally on that day it was a herald of the coming of Winter, where the community would bring in their livestock to avoid the cold, stock up and share food.
The kings of old would have held feasts, people got drunk and generally it was a time to celebrate life, not death.
The perception of danger was potentially due to perception filtering, because people were far more connected to nature back then. So sex and death were not seen in negative aspects. Customs were not written down and conversation to Christianity was, relatively swift, brutal and involved the Roman tradition of domination through cultural and political appropriation. So most if not all traditions were lost to time, with only the Christian historians to write their observations. So in the absence of information, the negative aspects may have held more interest.
The barrier between the Otherworld was understood to go both ways, so the living were equally at risk of accidentally wandering over, getting lost and coming back 200 years later, or getting blind drunk with some dead warriors loitering about the moors, or being abducted by mysterious, beautiful females from another dimension!
Source: https://youtu.be/c5QrcOJIZBg
