I’m certain ILM worked incredibly hard to get this effect, like they did with Tarkin, and that’s enough for me. Although I still think Sebastian Stan would have worked well, it’s a great thing that old Mark Hamill can still have a chance at playing young Luke Skywalker.
And I think they should know by now to stop burning money on this stuff that always fails and has to be fixed by amateur deep fake people online. Mark Hamill can still have the role, but when it’s so prohibitive (to the budget and the performance) they need to do it another way. Give him a beard, do practical makeup, do something else. It’s gonna age like milk. Evidently people haven’t complained enough.