CPUs simply push wider SIMD (SSE -> AVX -> AVX512), bigger out-of-execution buffers, larger registers, deeper branch prediction, more cache. The biggest advancement seemed to be Intel's uop-cache in Sandy Bridge (a concept that was first tried in the Pentium4, so not really a "new" innovation).
Even ARM chips are more of the same. Wider SIMD (see A64fx: #1 supercomputer in the world for 512-bit SVE), deeper out-of-order execution, better branch prediction. Its rare to see something new
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In contrast, whenever I see GPU-architectures, everything is so hugely different. True, GPUs all have a "SIMD focus", but there's so many exciting things about SIMD that just haven't been explored yet.
NVidia has Tensor-cores, Raytracing cores. It was already crazy that NVidia had a full matrix-multiplication implemented in its FP16 processor in Volta, but Ampere is now pushing sparse matrix multiplication at the chip level (!!).
AMD GCN and RDNA push GPU/SIMD architecture in a different direction. While a chunk of RDNA can be described as "more of the same", the "SubVector execution" feature grossly changes how Wave64 wavefronts are executed to save on register space and potentially have a better memory access pattern. Innovation continues in the AMD space for sure.
Intel finally enters with their GPU / SIMD architecture, and they start of with... SIMD8 + SIMD2 (instead of the Wave32 of RDNA/NVidia or Wave64 for GCN). Finally, Intel is minimizing hardware scheduling (saving on die area), and focusing on software to schedule the instructions.
Three very, very different architectures. Three very different ideologies for how SIMD compute / GPUs should be built. The SIMD / GPU architecture space remains more innovative than the CPU-architecture space by a longshot. Its exciting to see.
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I'm not saying that CPU-advancements are dead per se. AMD did make chiplets a hot commodity (but chiplets were already experimented with Power5, and chiplets seem like a natural evolution to dual-socket or NUMA architectures... just cheap enough for a consumer now). Intel's new Tremont Atom core has this cool "dual-decoder" design (where one decoder works on one-branch, and the 2nd decoder works on a 2nd branch in parallel). There are certainly new ideas being tested in the CPU world. But nothing as majorly game changing as what Intel / AMD / NVidia are doing to the GPU space. (Or Google if we include TPUs in the discussion. A TPU isn't SIMD, but it shares some degree of similarity, especially to NVidia's Tensor cores)
I guess big.LITTLE (and Intel's Lakefield platform) was a big change in the last 10 years. But that hasn't really seen much success in the Desktop/Server markets.