Because long-clicking takes so much longer? Think what I could do with all those milliseconds saved.
In the meantime, I still don't have the capabilities I lost recently:
1) sending videos via Google Photos. Extremely helpful when sending videos to iPhone users vs an overly compressed video
2) and the ability to snooze a particular message - within the app long clicking a message and tapping the clock to remind you later). This was so useful when I get messages while I'm at work and don't have time to reply. Now I either forget or I have to manually set up a reminder.