I'm gonna have a bad time against a frame 14 move that has a purely horizontal hitbox and is very easy to predict that it's coming out.
Yeah.
Sure.
I'll be more scared of Toon Link's almost 100 BKB 13 damage F-Air which hits like a truck KB wise for how much better his moility is.
Here's the other issue. You're trying to talk about using a frame 14 move to edgeguard with. That requires either a bad play on the opponents part, or a strong read on your part. No one is gonna jump into a frame 14 move, hell they won't even jump into a frame 12 move like Ike's F-Air. Even if Ike's F-Air starts on frame 12 it'll hit in the same area of Link's either on frame 13 or 14, depending on if they are slightly above or below Ike, which is either 1 frame faster or same frame as Link's. You also have air speed. Link's air speed is abysmal, and with a frame 7 jumpsquat, like Ike, it's much harder to go out and edgeguard compared to other characters with better jumpsquat and/or air speed.
How do you set up these F-Air edgeguards? You can't use a projectile, as they take far too long for you to be able to follow-up on unless you're going out and putting yourself at risk. Do you just jump out and try to hit them with it? That's predictable, so if they react correctly now you're massively at risk with a poor recovery and bad air mobility leaving you wide open to a reversal.
Yes, Link's F-Air hits hard, is it easy to use like how you describe? No. It'll kill Mario at quarter screen about the same as Ike's Dash Attack kills with no rage at the ledge percent wise.
Buffing can KB would also have a massive down side like
@outfoxd said.
Can combo breaker -> suicide?
10/10.