RS codes can be done in N log N time for both encoding and erasure decoding, and sometimes achieving MDS is useful for attack resistance... e.g. that you can always decode with N blocks, vs with non-minimum distance codes you can have adversarial subsets that will fail to decode even when you have significantly more blocks than needed.. Larger word sizes for RS codes is also useful for list decoding even when the number of data blocks isn't that great.

And sure, list decoding is slow. But I think there are two distinct groups of applications for good instruction sets: one is where you're trying to make a fast thing like an 8-bit RS code or something "free" by having it run at near memory, wire, or disk speeds (or make it consume little power). but the other is where you're doing something legitimately slow, including things that are O(N^2) (or worse). In those cases sometimes a small constant factor makes a big difference between usable and very much not usable.