I don't see that full sus' is a progression of/from hardtail, it's just different. The skills you learn on each are transferable to the other, with only a bit of adaptation of your technique.
...much faster on the down bits than I ever was on the HT and also there is a lot of truth in the skills thing - I've topped out on the HT, never going to get any better as a rider and the F/S seems to compensate for that a bit, my confidence is coming on a bundle.
To me, the appeal of hardtail is that it is much easier to find the limit; it is where the fun, enjoyment, buzz, rush, whatever... resides, and I don't have to be going so quickly to find it. Again, one isn't a progression of the other, it just provides a slightly different experience.