I would love for Ableton to also include a feature that exists in both Logic Pro and Pro Tools: Modulating the pitch of audio files with fade envelopes.
I'm proposing that we also be able to use volume fade envelopes in the arrangement view as a way to modulate the pitch of audio files. If you draw a "pitch fade" at the beginning of the clip it would start at a pre-determined lower pitch and then varispeed itself up to it's neutral (recorded) pitch. Conversely, if you used a "pitch fade envelope" at the end of an audio clip it would varispeed the pitch down.
Of course, Ableton can already modulate pitch in the envelopes menu, but this particular type of pitch modulation is far harder to do using Ableton's capabilities, whereas the process is far simpler as it is implemented in both Logic Pro and Pro Tools.