If you want something for a “simple IRC client”, users can just have a simple app that gets run before irssi/mIRC/xchat/whatever, checks if the token is expired, if it is refresh it and save to the appropriate clients config file, launch that client and terminate the app. Would add a minimal amount of delay, and only happen when launched.
Some IRC clients could even do this internally with scripts and not need any extra app.
Is there some annoyance with token expiration? Sure. But it reduces a security issue and once you automate token refreshing it’s not a big deal as the overhead to maintain a valid token is minimal. Plus this is already a very niche subset of Twitch users that this will be an issue for.