Shoudn't abilities cancel when the champion is stunned?

I just played a game with twisted fate, which I did absolutely horrible in, and I realized how useless his stun is. His stun lasts one second. If I stunned Ezreal or Reksai, they would still burrow or "teleport"(don't know how else to describe ez's ability). Those abilities take about a second, so my stun is up by the time they are done. To me, that's garbage. Stuns should cancel their abilities.