I think a #1/2 dman is a bigger need at this time, especially considering one is possibly available (doesn't happen as often as a top 6 winger).
Yes, the Avs forwards had trouble burying the puck in the net this year, but this same bunch has had good scoring success in the past. I expect them to score better next year, even if we kept the same forwards we have right now.
The defense, however, will not be better next year if we keep the same group of guys we have now. A #1/2 guy would bump the #3/4 guys down to where they belong, allowing #5/6 slots to be filled either by guys currently on the roster, or rookies (Elliott, Barrie, or Gaunce).
They most certainly need to add more firepower up front. The question is whether they need to break the bank in order to do so. My answer is no, they don't HAVE to get Parise to have a legit offense, and upgrading the offensive punch from the blueline will help in the scoring department anyway. What they can do is look for upgrades amongst the lower-tier scoring options available on the market. No, not Semin, but there are others.