It's possible this is somehow related to new DOT regs that went into effect last October and require when travel vouchers or credits are issued as compensation, they must be valid for at least 5 years. However, airlines may offer cash refunds as an alternative if acceptable to the passenger. My guess is they don't really want to keep track of the vouchers (and account for them on their books) for 5 years and are shifting to the alternative cash refund offers as compensation instead. I believe there have been some similar reports in DL forum of DL issuing refunds in certain cases where they would have issued vouchers in the past. The same new DOT regs defined "significant delays" for schedule changes and IRROPs (3 hours for domestic, 6 hours for international), where passengers are entitled to either request a refund on non-refundable fares or airlines can offer compensation if acceptable (although they didn't mandate a particular amount of compensation).