I agree that it needs an animation, but for a different reason than just the coolness factor.
Her ultimate is one of the most powerful abilities in the game. I would argue that, situationally, it can be more powerful than a Taric ultimate or a Ryze ultimate.
It comes out instantly and flies so fast that players who don't have Challenger-level reaction times simply cannot react to her firing this at you in the middle of a normal lane phase, and even if you do have Challenger-level reaction times, you HAVE to be playing a champion with a strong dash or have your flash up to be able to dodge it.
Yes, an animation would be pretty great visual-wise, but it would also allow the power of this ability be reigned-in a little bit more. As it stands, if Riot gives Ashe buffs, they end up having to revert the buffs later and then nerf her more because her ultimate is just too strong to allow the rest of her kit to be on-par with most champions as well. If she's equal to the average ADC in pre-6 lane phase, post-6 lane phase Ashe is just busted, as we've seen in these last few patches where, yes, Ashe was strong, and they nerfed her, not only reverting the buffs they gave her earlier this season when she was too weak, but nerfing her to a state where she's weaker than she was before those buffs even happened! And why is because this ultimate is much too powerful to be allowed to exist on a champion who also has the rest of her kit be even average. I had a game once where I was extremely fed (like 6/0) on Twitch vs an Ashe, she's off split pushing, I go to assassinate her (she's very far behind), and she just presses R and kills me, and because I'm standing within my 850 unit autoattack range that my ult gives me, I can't react fast enough to stop her from stunning me for 2 seconds and then killing me in that time.
Her ult is, as it stands, essentially a 1.5-2 second basically targeted stun if you're standing anywhere near to her. Jhin's W doesn't even have any cc unless they're marked, and even then it doesn't stun, and it has a delay on it and a thin enough hitbox that it's honestly pretty hard to hit. Yes, I know that it's a basic ability, but its cc is gated behind so many things, you have time to react to it, and it's overall much more balanced than Ashe's arrow.