Swong, an SPIA and the annuitization of a DB plan are very different animals, although similar in some respects. Also, the decision process with a DB plan is forced upon us, and must often be responded to in a relatively short period of time, whether it be a few months or by age 70.5. On the other hand, we have total control over an SPIA decision. As for RMDs being higher for an IRA as opposed to a like value annuitized DB, that might be true in later years, but the opposite is true in the earlier years. On the IRS Uniform Lifetime Table RMDs start at about 3.65% payout, and don't reach common SPIA payout rates until about age 85. Hopefully as the RMD payout creeps up, so will tax brackets, although that doesn't seem likely. The likely reason this worked out for you is in part because of the NYS $20k exemption.
I would never fault anyone for taking the annuitization of a DB plan. It should be the default position unless there is good reason to the contrary, such as marginal health, or it is more than the PBGC insurable amount, or it's in a plan that isn't growing and it's not inflation indexed, or it's just a great offer, which does occasionally happen, etc. I just triggered my lump sum today...I wish the market weren't so high