i expect companies that remain private while dangling equities for it's employees to create an opportunity for them to sell privately - e.g., a liquidation event, where the buyer is an investment/VC firm that wants in. It's good for both parties - employees get a liquidation event, the VC gets foot in the door, and founders aren't diluted.
I guess, though, in this case, the employee is the party without power, as they are offered a price (which is probably lowballed, since they don't have a choice) in a take it or leave it fashion...
I was at Dropbox for a while and left in no small part because of the frustrating lack of potential liquidity on my equity.