I think it's more about accurately assessing available talent and team needs. Guy and Lechler might be the two best punters ever and they were both drafted by teams that were otherwise ready to compete for Super Bowls. Similar for Janikowski as a kicker, although he didn't quite live up to his talent.
I can see using a 7th rounder on a punter or kicker so you ensure you get your guy and don’t have to compete with other teams in undrafted FA but the 49ers have hit on a lot of really good players on day 3. I would rather swing for the next kittle, Greenlaw, Jennings, Hufunga or Purdy than take a punter or kicker.
I think you'd be singing a different tune, if he had turned out to be an elite punter. That roster was otherwise stacked already and only sucked on special teams.
Classic NFL wisdom: never draft kickers, punters… or running backs before round 5. Harsh reality of roster math. Mitch had a leg, but durability’s the hidden stat no one scouts well enough.