One of the chief criticisms of annuities is their relative lack of liquidity. This is true in some respects. Annuity owners give up complete liquidity in exchange for other benefits, including insurer guarantees for lifetime income, guaranteed growth, or protection from downside risk.
Many annuities now come with guaranteed income riders that can be turned off and on while letting you still access at least some principal. And most contracts do offer something called "free withdrawals."