I mean, H/B were over 20 points behind H/D at Worlds last year too, so I'm not sure why that number itself is so surprising. If we want to talk about Fear/Gibson, then here's a little breakdown of the FD:
PCS - H/B won SS and TR, F/G won PE, CO and IN. That makes sense, though I would give H/B a bigger gap for SS especially.
BV - H/B were 0.75 higher, because they have level 3 on the step sequence while F/G had level 2. All the other levels were the same.
GOE - H/B got 18.15 points in GOE, and F/G got 21.98. Let's look by element:
One foot steps - 0.2 more for H/B
Midline/Circular steps - 0.14 more for H/B
Spin - 0.16 more for H/B
Solo lift - same for both
Twizzles - 0.41 more for F/G
Combo lifts - 1.44 more for F/G
Character step - 0.47 more for F/G
Choreo slide - 0.83 more for F/G
3rd choreo element (spin for H/B, lift for F/G) - 1.18 more for F/G
So the big difference is in the lifts and the choreo elements (especially the choreo lift). H/B have never had the most effortless lifts, from what I remember, probably in part due to their height difference. But also, Lewis is a really, really great lifter. Their combo lift is insanely cool and really difficult and well-executed. So they are not easy to match there.
I haven't gone back to watch, to really analyze each element, so I can't be super specific. But I have seen some people saying that the FD is a bit dense. That was also said about V/M's original Moulin Rouge, and they had to rework it to give themselves more room to breathe and to show off the quality of their elements and skating. That might help H/B earn more on the steps and in SS. And adding a bit more lightness and humour to the program might help them make the choreo elements just that bit more special.
I do think it's really important for H/B to maximize points on the steps and things, since they don't get the most points on the lifts, which are worth a lot.
I think their RD is really good, and the FD has a lot of potential, but it does need to be reworked a bit - and they need a clearer concept of the program, imo. Currently it's kind of convoluted, and I think that comes through.
Thank you! Maybe you should have a job on the Olympic Channel doing ice dance analysis! Or at least be on payroll of the Montreal school!