Upgrading a Twilio account can be beneficial for developers who want to explore the Twilio APIs and coding projects, as it allows them to keep their trial minutes instead of losing them. When an account is upgraded, unused minutes are credited at $0.03 per minute, which can then be used to purchase any Twilio service with the account. This feature is a thank you from Twilio for using their service and upgrading to a paid account. Additionally, developers can take advantage of multiple Twilio accounts to manage different applications separately, allowing for better organization and debugging capabilities.