They also appeal to investors who want to invest in something other than what 529 plans offer. (529 investment options are limited to what the plan sponsor offers, much like an employer-sponsored retirementplan).
The technique is known as dollar-cost averaging, and it's essentially what you do when you invest a set part of your paycheck every pay period via a 401(k) or other employer-sponsored retirementplan.
Effective Jan. 1, the federal government dropped the income limit for transferring savings to a Roth IRA from a traditional IRA or an employer-sponsored retirementplan, making it easier for people with higher incomes to take advantage of Roth accounts.