People tend to look back at the past and romanticize and simplify it. We use it to justify our agendas, whether they are political, ideological or spiritual, but how often do we stop to think that we are doing our ancestors a grave disservice.
We dishonor the struggles they had and we judge them, by our standards, not their own. We take their lifestyles and beliefs out of context and try to squash them into our world, but we very likely, don't understand those practices and beliefs the way they did. From the perspective of an anthropologist, who has studied historicity (the process through which history is written), these are acts of incredible violence and callousness, often directed at preliterate indigenous peoples, who for generations have had their lives, livelihoods and culture stolen from them for the profit of Europeans (and their far flung descendants).
In the spiritual/metaphysical/religious practices being packaged and sold in books, websites, and lectures, many old customs are being dusted off, repackaged and often sold without context or real respect for their origins. many of these practices, if we don't get carried away by our fantasies of the past, can be useful for cultivating spiritual health, but we should also invest some thought and energy into trying to actually understand them, as they were created, rather than how they are sold to us, to honor them and their creators.
When we get caught up in toting the ancient origins or beliefs of long dead people (or peoples, as the case very often is), we are not accepting ancient practices, we are borrowing a name to defend our own ideas. It is one thing to be drawn tot the mythologies and artworks depicting ancient gods and goddesses, but it is another thing to declare ourselves new practioners of ancient practices, when a great deal of metaphysical thinking and neo-pagan practice is a product of rather recent historical moments, wherein the "ancient" beliefs are the products of someone's imagination, not, as they often claim, the uncovering of ancient texts.
If you are drawn to a particular belief or set of practices, do yourself a favor and invest some time in learning about them, from the viewpoints of a devotee and an academic. There is nothing wrong with creating spiritual practices, but don't appropriate someone else's especially if you don't know what you are talking about.