Starting us at a blank slate is not progress, it's repetition; there is in fact a difference. As for the ultimate goal, I sort of thought the goal was to spend years building up a legendary guardian who reflects the cumulative work and choices of those years; that's not going to happen if last years work and choices are thrown out when the next year starts. In fact if all our gear is becoming obsolete and everyone is starting at a new base level what's the point of keeping our characters in the first place?