I feel that the New Age movement, at some point between when it began in the 1970s and today

It didn't begin in the 1970s. The biggest propagator of what we would call New Age ideas today was C. W. Leadbeater (1854-1934), the most influential occultist of the 20th century. Some say it's Blavatsky, but she only built the foundations, and he was actually the most influential, whether you like it or not. Most people don't mention him, many hate him, yet all of them got influenced by him. His ideas are literally EVERYWHERE you look around in the New Age movements, they don't have any other author than him, most of them. Here's a quote from his biography:

The modern occult revival owes more to him than to anyone else ; his concepts and ideas , his popularizing of occult and Theosophical terms and principles , run through all modern works on these subjects .

The idea of reincarnation , and of investigations into life before birth as much as life after death , ideas of ‘ reincarnational therapy ’ and examinations of the akashic records derive directly from Leadbeater’s work .

The concept of the aura , the bio - energetic field surrounding the human body , which is currently attracting serious attention even in orthodox scientific circles , was first made popular in his writings , and first extensively described by his accounts of his clairvoyant investigations .

Not even mentioning he also discovered J.Krishnamurti who was incredibly influential to the West. If anyone is willing to argue that JK is an independent thinker and he would have equal influence if Leadbeater didn't take him under his wings, I'd be more than happy to provide numerous arguments that C.W.L made J.Krishnamurti, and his huge influence to the West is really on Leadbeater's account more than on JK's account!

So that's for influences, and that's the most important thing, because most of the ideas were there somewhere for thousands of years, so it only matters who made them mingle the most! Origins are much earlier of course even of the pure New Age movement.

When it comes to an evaluation, and the "debate part" there isn't much to say. What you defined as New Age is a pathology, but it's an inevitable stage of the religious culture clash. Once the cultures clash, the religions will have to mingle, they are no exception in the world where everything is ruled by the same laws.

In the future we can only speculate what will happen to the community, but the mingling of those ideas to an astonishing degree is almost guaranteed, what's also guaranteed or possible is that people will have more and more religious freedom to choose their religions, and, as we all are really flawed, the majority will always choose something bad, something harmful, something wrong.