I'd hope saving a year for Jackson isn't a factor, only mentioned it because it's a possibility as to why he's only been in one game so far.
Maybe Denaburg is the best option, but he's a career 61% kicker (19 for 31). You are right that he's 6 of 9 this year, but only one of the makes was over 30 yards. Ligashesky brought him in from Syracuse, so he knows what he is and isn't. Maybe he thought he could fix him? Who knows, but whether it's mental or mechanical, he's proven unreliable at distance. His career long is 46 yards. On kicks longer than 38 yards, he's made just 3 of 12 (including a block). This year on those longer kicks he's 0 for 3.
If Jackson is so much worse in practice that they have decided he's not a viable option, I agree with you that we should just take the long FG out of the tool bag and go for it or return to punting from the plus 35.