These devices lasted 15 years in some some cases.
But videos not playing correctly was too much. Hardware vendors should develop H266.
There is something for you to understand here:
CPU/GPU "intensiveness" of a codec depends, and an increased computational overhead of newer codecs is always to be expected. The more efficient a coded (perceived "quality" per bit), the more complicated the computations of decoding need to be.
That's why most (consumer) CPUs built in the last decade have hardware decoding support (having a dedicated hardware implementation is always more efficient than running on the CPU) - and often even hardware encoding support.
The difference between h26x decoders must not need even that big (depending on the implementation). Widespread use of h264 killed most notebooks because of the missing hardware decoder.
h266 would with 99% guarantee never run more efficient on the same hardware than h265, unless we find some magic to achieve better-then-h264 encoding with MPEG1 complexity, and if this was easy, why was h265 not that.
And then there is AV1, which makes any newer MPEG-LA standard pointless anyway. You just need to wait for the respective widespread use of the hardware en-/decoders (and efficient encoder implementations I guess).
That doesn’t have to be true. Only encoding is guaranteed to be more intensive.
What happens when more efficient encodings are developed though is usually not bitrate going down, but instead it is kept on the same rate to provide a higher image-resolution/quality for the resulting video.
And that means more pixels to render, and that means more work on the decoding end.
It's more CPU/GPU intensive, is not as widely supported, and there probably are more downsides.
Better quality at the same bitrate? For most use-cases: yes.