Ah.. true enough, I remember the filters on my old SQ1. Still it's a colour thing I guess, I'm more than happy with the software filters I have now, especially the ones from Fabfilter. As in they sound far better, and their response is far, far sweeter. Talking of Ensoniq though, the piano lead on the SQ1 I still don't think has been rivalled by a purely software equivalent. But that could just be down to the physical response of the keyboard, which was wonderful.
I doubt there are things that 'software can't do' more than a bit however. The opposite actually holds true, as in you can build signal paths and modulation dependencies very easily that purely hardware solutions could never do. Which is one of the good reasons for choosing and using software solutions.
'Weird things' with start times/velocities are easily done in available software, and can even be wired to trigger/control parameters in completely different filters, gates, busses and on completely different tracks if you like. I can even write morphing scripts with Kontakt too.