Think about the company's employees. Especially the ones who joined early on. They are usually working nights and weekends hoping for an IPO or a buyout. How do they feel about this?
Actually, the trend does seem headed this way. Just as the balance between founders and investors has been shifting, so it is shifting between founders and early employees. Scarcity in the hiring market for top talent is one indicator. It is bound to be exacerbated by the fact that creative people who want to work at a startup can easily just found one themselves. We may see the line between founders and early employees blur over time.
None of this seems very troubling. It looks to me like creative people being rewarded more, and earlier, for value they add. Perhaps it is more troubling if one has nothing to add but money. But even that seems short-sighted. Why not maximize the total value created?
Otherwise, an early employee would have to wait/work years longer for the actual equity event (if it ever comes) to find out how they will be treated.