Variable rate shading is transparent to the user, and it "only" boosts performance, and according to the results
we've seen from Ice Lake U presentations, it's mostly useful for GPUs that lack raw compute power for its segment (i.e. not most AMD solutions).
Lack of DXR will mean a constantly greyed-out option for every AMD user. That has a whole different impact.
In 2018 I think the feature was completely useless. In 2019 it's still not very useful but it's definitely a long-term feature to pay attention to.
But in 2020 (6 months from now)? Well in 2020 we'll have Cyberpunk supporting it. And Cyberpunk will most probably be
the system seller of the year.
And people spending $450 on a newly released 5700XT next week will have a greyed out IQ option in Cyberpunk.
AMD definitely knew DXR/RT would be widely adopted by 2020. They knew because they've been designing the console GPUs that support RT hardware.
Which is yet another reason why Navi was most definitely not an architecture designed to release in H2 2019. These should have been releases for early Q4 2018 at the latest.