Ticket numbers are good enough as long as they don't rot (i.e. you never permanently delete tickets). That's just writing the "why" somewhere else instead of in

Ticket numbers are good enough as long as they don't rot (i.e. you never permanently delete tickets). That's just writing the "why" somewhere else instead of in the commit message; the important part is that it's written down somewhere and is discoverable/accessible to future folk (yourself included). I like putting a minimal description in the message itself too so it's easier to skim the log, though.