Basing the argument on single company stock reliably going up is a big mistake, but I do think the longer-dated stock awards are advantageous to many employees

Basing the argument on single company stock reliably going up is a big mistake, but I do think the longer-dated stock awards are advantageous to many employees because they're effectively an employee option - every month/quarter/year you have the option to quit for a market rate job elsewhere or accept whatever the stock is worth. Also if a stock dips many employers in competitive markets will end up compensating somehow. It's difficult to model because it depends on how employers behave and how much they want to retain you. If they reliably give you extra grants/bonus to get people back to target compensation after a decrease in stock price, then the downside risk of longer-dated grants is reduced a lot, but you still have significant upside. Reality is that people don't want to job hop always, not everyone can easily find a market rate job, employers don't 100% true people up after a stock dips and and employer might not be invested in retaining even a good employee. So YMMV.