I'm afraid Strong would give Calvin too much of a "Timmy Turner" voice, which is way too hyper for Calvin's intellect. Frankly, any voice you could give him would sound wrong to me. Same problem with Hobbes. Williams has a too-recognizable voice and it doesn't match my imagination.

I think Watterson said somewhere that he hoped that no one would ever try to give them voices. Their written words are powerful, poignant, childish, and adult all at the same time--not at all like modern cartoons.

he says the only reason he hasn't had an animated calvin and hobbes is because it'd be too frightening for him to hear calvin's voice. so even with a talented voice like tara strong he wouldn't be on board with it