Sam Altman advocates for a longer exercise window [0] as part of his piece on employee equity. More early-stage companies are adopting it, but it's not without complications. For example, 90 days after termination ISO shares convert to NSO shares, which are a different beast for taxation purposes -- employers/employees rarely understand ISO shares, let alone ISO+NSO.
I think thats a good move in the right direction, but the fact remains that startups are risky in general. Taxes + the exercise price of a slightly less risky startup (higher strike price) can unexpectedly add up to quite a bit of money for employees less familiar with stock options. It would be cool to find ways to diversify that risk or sell part of it to someone who is willing to take it on.
[0] http://blog.samaltman.com/employee-equity
[1] I work @eShares.