"Gerryirish" sounds like he'd be in a better position to answer that, but I have celebrated it in Irland more than 20 years ago, and the anglo-irish family I was with, and their neighbours, decidedly saw it as being the celtic harvest festival, with no christian association whatsoever, apart from the english name halloween, being "by coincidence" on the same date. My guess is that if not for the celtic "Samhain", nobody would care a hoot about the christian "all hallows", it would be at best a watered down tomb-sweeping-day.
It's not so big in my country so I don't know the popular meaning, but my suggestion would be to find out which meaning is more popular (perhaps on a country by country basis), either Samhain New Year or All Hallows, and then re-affirm that name & promote that meaning.
"when I ask the 'why', people usually say the 'what'"
That's exactly how it works in China. The "why" often doesn't get answered because it has no weigh, importance or people just don't want to admit that they simply don't know about it.
That is a sad situation. But do we want to become like that too?
I'm often confused when people use "we" or "us" on Chinese expat forums. Who are "we" and "us"?
We Westerners I meant. We haven't had the unfortunate conditions that led to the loss of many traditions the way the Chinese have, but are we going to throw out our cultural traditions anyway?
By definition, I am not a Westerner, so I am probably not an "us", but there is no current reason why people who know the meaning and reasons of the festivals that they celebrate should forget or willingly neglect those.
If people are willing to celebrate anything that gives them the impression of sharing joy and happiness just because it's mainsteam or because everyone else does it, then you can introduce anything to them under the disguise of positive emotions without them caring about knowing the initial meaning, even if it's teaching them something positive/negative or good/evil.
"there is no current reason why people who know the meaning and reasons of the festivals that they celebrate should forget or willingly neglect those"
Sadly there do seem to be people who know the meanings of Western festivals such as Hallowe'en and Christmas but only engage in the superficial commercialised forms and neglect the meanings and reasons of them. However I don't know what's going on in their hearts, so perhaps they remember the meaning on the inside! After all as you said, there is no reason why they should willingly neglect the meanings.
If a festival means something that you do not believe in, e.g. xmas for non xtians, this does not mean that you should not partake in the celebrations, just because you don't believe. By extension it is OK to neglect the meaning in many cases.
I partake in tomb sweeping with my Chinese family. I would be crassly offensive if I did not kowtow at the ancestors' tombs. I am not worshiping idols, because I believe they are just remains. It is a grand day out for the extended family, with a picnic.
I am not a Chinese person, but at spring festival I would not deny the kids their Hongbaos. I am not a practicing xtian either, and I would not deny the kids their xmas presents.
As for the arguments about losing the 'real meaning', Xtians hijacked all of the pagan religious festivals, so stop people slipping back into old ways. To me this was more extreme than the dilution of religious festivals by commercialism. And I bet this dilution/merging of festivals has happened in every culture over the millennia.
If you are religious and hold certain festivals as sacred, fine, good for you. If you expect everyone else to do the same, that could be likened to puritan bigotry.
What would be the alternative meaning? Or do they become meaning-less festivals?