Apple has online feedback forms for many applications and products (Apple - Feedback).
For feedback on iCloud you may want to use this form: Feedback - iCloud - Apple
Apple promises that all feedback sent in will be read, even if you do not receive a reply. You are welcome to post constructive feedback here in the forums as well, but it is not guaranteed that the developers will read each and every discussion, so your contribution here may go unnoticed.
The preview of High Sierra is here: macOS High Sierra Preview - Apple
If you scroll down, you see what will be new in Photos and for Live Photos:
When editing a Live Photo, try the new Loop effect to turn it into a looping video that you can experience again and again. Try Bounce to play the action forward and backward. Or choose Long Exposure for a beautiful DSLR‑like effect to blur water or extend light trails. You can also trim, mute, and select a key photo for each Live Photo.