As a couple retiring in our 30's, I didn't want to be locked into a specific income stream. If we ever took jobs in the future we would not be able to control total income in a year, which could have undesired tax consequences. We have more than enough money in taxable accounts to support ourselves for at least 5 years, probably a good bit longer. We'll start the Roth pipeline as soon as we're both not working but we probably won't need to withdraw any money from it immediately (5 years later).