A: You have no control over those funds anymore. You are at their whim.

B: You are at the mercy of their financial health for as long as you live. This is also a good reason why to have Defined Contributions and not Defined Benefits, as with Defined Benefits, you are at the mercy of the health of the employer for as long as you live.

C: Your payments don’t go up with inflation in many cases, and even if it does, it’s not without a high cost for it.

Your A and B kinda fits into my C.

As such, I will rather take the lump sum method with my set of financial and investment rules over annuities.