> I can see the importance of this from the company end - with tech company shares skyrocketing, a fixed share amount gives them potentially unlimited stock compensation liabilities which could drag on earnings.
AFAIK that is not how stock works in this context. The company issues the shares ex nihilo. That dilutes existing shareholders (if not offset with buybacks) but otherwise doesn't cost the company anything. The shares are not vested so if you leave they return to the comp pool. The company doesn't magically issue new shares on your vesting date so any rise in share price doesn't affect the company anyway. The whole point from a company POV is they can pay you in paper (shares) they manufactured out of nothing rather than cash.
They are doing it this way to reduce the total number of shares they need to issue (aka cut compensation). There is basically no upside for an employee, the changes to vesting schedules or cliff are a sop to avoid having to tell their employees that they're cutting compensation. Employees can already borrow against those RSUs if they need money.
The idea that missing out on a 10%-200% rise in the share price over the next four years in exchange for a bit more flexibility in vesting is a joke. If the company actually cared about the flexibility they could just switch to 6 month vesting or monthly vesting without removing the upside. There is no benefit to removing the upside beyond reducing dilution. They sure as hell aren't going to apply that same policy to their executives.