I feel Arthur's lost its touch. Episodes like the one you cited were pretty much what made Arthur itself.
The slightly deranged animal people world where all the kids learned how to get along with one another - it was quaint. Not extremely deep, but charming enough.
I think the problem was they tried keeping the same format after they've used up all potential storyboards - instead of trying anything new past the 5th season, they decided to rehash most of the series without adding much to it. Arthur and the others are perpetual third graders, continuity is loose at best, the same storyboards used up already were done over and over again, mixing and matching characters used per plot. The decline in animation quality (FLASH) didn't help matters. Arthur was never "The Prince of Egypt", but it did had fairly nice animation and style compared to other shows of the period.