I suspect it is a Mediterranean tradition originally - places where almonds grow in abundance. In Italy they are known as 'Confetti', which I think translates as 'little sweets', but obviously that means something quite different to us.
I've been given favours at pretty much every wedding I've attended in the past 30 years, so it's definitely not a new thing, and I have always been aware of the associated symbolism.
Off on a tangent, sugared almonds always remind me of Xmas, since that's the only time they appeared in our house, but even as a child I couldn't crunch them. I certainly wouldn't attempt it with my current (precarious) state of dental health!