How do we infere that time even "exists" in the first place? By movement, of course. We know that an hour has passed because by a predetermined convention of "ticking cycles" the small hand on the clock got from one number to the other. We know that a day has passed because the Earth did a full rotation on itself and we see the Sun in the position we predicted based on calculations. Those experiments that mention that time has slowed down on top of a building vs on the bottom or in space vs on Earth basically just take into consideration the measurements of some sort of clock, the MOVEMENTS of the clock mechanisms.
As for time perception, more and faster movement is perceived as time going slower, while less movement as time going faster. For this, I like to think of the concept of frames per minute. Think of a movie from the 1920s, the movement of the characters is choppy because they used less frames per minute. When you compare it to a hyperrealistic movie from today, where more frames per minute are seen, the character from 1920 will be perceived as moving faster.
So my point is: time is a convention used to explain movement. There is no time per se, neither here nor in the astral. There is only movement and its perception.
What is movement? Is the act of something (a body, a particle, a wave) going from location A to location B. Location B could be microscopic and/or even within itself (thinking of peristalsis). For movement to exist, however, we need space to exist. Although the opposite may also be true. Can there be a space where absolutely nothing moves? It would have to be a place where there are no atoms or subatomic particles of any kind and is unaffected by physics. I cannot think of any place like that.
Are we here to experience time? I'd have to rephrase, are we here to experience movement? I would have to say no, as nothing indicates to me that there is no movement in the astral, things just move differently, therefore they are perceived differently. Is movement necessary to exist and evolve? For sure, movement is everything.