I've just realized this after playing Irelia: at 60 ms, my latency is too high to pull off more than two Bladesurges in a row.
The first and second are instant, because the second is buffered, but my latency delays the third by so much that it's noticeably detrimental. This makes it impossible for me to play Irelia as effectively as someone with 10-20 ms latency, and gives them a significant advantage.
An obvious solution to this would be to allow abilities with cooldown resets the ability to buffer more than one. There's really no reason for these abilities to remain like this.