You're mashing together a lot under "gimmicks" there.
Texture compression: Useful for games, ongoing work, although I wish they would make cards with appropriate amounts of VRAM
Lighting tricks: Not sure what this is referencing
Improved antique video encoders: NVENC started out with only h.264, but now it supports h.265 and AV1, which aren't antique at all. Niche, but widely used in the streaming industry.
Motion smoothing: The hardware optical flow accelerators in newer cards are important for DLSS, which is a bit gimmicky but works mostly as advertised.
Bad proprietary vrr: No argument here, gsync sucked.
Ray tracing: All 3d games are going to be ray traced sooner or later. Getting a head start on it is a good move, and it's a big head start. The 4090 is ~100% faster than the 7900xtx.
CUDA: No one can seriously call CUDA a gimmick.
Machine learning features: Tensor cores are great.