3. (From zero authority here as I’ve never bought a company:)

Perhaps the acquired employees might prefer this for tax reasons. If they stand to profit mainly via capital gains, that is wildly better than receiving ordinary income, like a bonus, would be.

Or, a completely different, unverifiable possibility:

An acquisition does not set any precedent for compensation of any kind. As a general rule corporations hate paying humans, but don’t mind paying other corporations.