My thoughts are along the lines of Trevor's. I'm not a New Age follower, but the New Age belief has opened up the idea's for Lightworker's when they made known their own Lightworker's that they call "Indigo Children". The only difference for me is that I think Lightworkers, (and this is a VERY broad term), have come from many different places and sent here for a particular reason during this specific time frame, which is probebly why their is an influx of Empath's. I believe it's been a long,long time since we have had this many Empath's/Lightowrker's on the planet during the same time period. This usually happens when the earth is going through a transition and the extra light energy is needed in order for the planet and it's occupants to evolve into the next phase.
There are alot of different theories about this and most of what you will find will be more New Age, and this may be a great place to start your search. For me, I feel this influx of Lightworker's are coming from all of the place, the higher realms, the Angelic realms, other planets, like a Universal beacon was sent out to everyone saying " send in your troops!" I do believe this probably started in the 60'sor 70's, like they believe when the "seeds" were sown. What I did notice is a huge mystical energy that poured in during the 80's. This energy is pure energy and not really programmed so it could be used however people chose to use it. The New Age and alot of higher spiritual groups came in and used this energy to draw in more light energy, but I also noticed alot of lower energy groups such as satanist and just humans in general also using this for their things. Satanism started making way, gangs started growing, the use of Ouija boards were at an all new level and bringing entities from all different types of realms. Magickal practitioners, our "powers" were heightened during this time so the mystical energy was being used for all kinds of things! But that mix of uses often also creates an inbalance. It was a time when the veils were at it's thinnest and the doorways to all the worlds were practically wide open. This allowed more Lightworker's to pass through, but it also allowed other entities the same privilege. Then the 90's came, the doorways closed and the computer age gave way to all new level. Even though technology turned into an all new high, mankind in general, I don't think were or are ready for it. We got the internet and this opened the doorway for alot of great things, bringing this planet more global, but on the flip-side, mankind as a whole has plunged itself into a very dark place because of it. People spend more time gossiping on social media then spending time with friends and family. The are loosing jobs because of the addictions the internet brings. Marriages and families being destroyed, due to rumors, cheating, porn addiction, facebook, gambeling, gaming, anything that can create an addiction. This has desensitized the planet as a whole. People have talked about a new dawn, a new era, and I believe this will be true later on, but I feel we are in our dark hours before the dawn right now. And once all the Lightworker's leave, the planet will plunge all over again, resetting itself and forcing itself to go back to their roots. Things are inbalanced right now, where darkness over shadows light, which is why I believe we are here, not to just bring in light and shift the pendulum to all light, but to bring in enough light to create a balance of the two so man kind can choose and have a fighting chance. I believe the seeds we sow while we are here, will mature when we are gone and this will be the hope that will be needed in order to push them into this new era.
Again, though, this is simply my theory and observations and you probebly won't find this anywhere, but if you do research on many different areas such as "Indigo/Crystal Children" , "Lightworker's", " Earth Angels", "Empath's" , this ay give you more information and a broader spectrum to come up with your own conclusion and purpose for why you are here. If you want to look further into my theory, you can also look more into the darker areas of paranormal activity, ghost sighting, satanism, witchcraft, mediumship, and even religions. You can also research statistics on both the helpfulness and destruction of the internet to get a baseline of where people are at in general and it's overall usefullness towards evolution or devolving. There's may different ways to take this subject, and all these tools are useful, but your truth may help surface through research, but it will mostly be within.
I hope this is helpful and I wish you many blessings on your journey