In T2's case, I think the bigger fault is with StudioCanal which owns the rights and does the transfers. And Cameron is probably to blame as well.In GBU's case, maybe they were trying to recreate late afternoon desert hues? Misguided but (probably) well-intentioned - just poorly executed and unnecessarily revisionist. Glad the yellow is gone.
To the poster who lamented about T2 and other "cursed" films - it's studio luck of the draw. T2 has the misfortune of being controlled by Lionsgate - a "studio" who is only interested in their portfolio. They may as well be a pharmaceutical company or a Real Estate conglomerate. I guess as long as movies are financed by shareholders and investors, they'll always be treated as product, not art as they should be.
As for TGTB&TU, I'll be picking this up. If I recall correctly, the Kino Blu-ray release had an issue with raised blacks. Seems they went the opposite way. Still might end up being the best this has looked on home video. And it'll be nice to have the shorter International cut again.