I suppose that over time it has been conflated with May Day, Walpurgis, Mischief night (not the Halloween version obviously) and the mid point (spring equinox/summer solstice) idea has been lost.
Lets face it though, most modern paganism is "modern" - recovered, reinvented, etc. I doubt that anyones practice is "authentic" and I gave up being annoyed by this some time ago - I think it is nice that folk do these things, even nicer when they think about it and its meaning. I even enjoy some of the stuff the xtians do!
Will you be doing anything tonight? Some say you have to extinguish and then re light the fire, others just make do with one fire, and others think that the right thing to do is process between two fires - as an anglo saxon it may be that none of this is relevant to me (yeah, everyone wants to be a "celt" but what can you do?).
The Pagan Federation generally tell people to do whatever they feel like doing.
I would love a time machine so I get some idea of how and where Bealtaine was celebrated (probably nowhere near a stone circle) but I suppose if time travel were possible it would be here already.
Love
Wiggy