What possible downside would there be to building an AI driven ship of some mass that can suicide through larger ships like that?

And why didn't the CIS issue Kamikaze Starfighter Droids to constantly rush the very vulnerable bridges of enemy frigates? It's an even easier, more sensible tactic for the CIS in particular but no one's ever complained about that. See my issue with the controversy over all this is why is this an issue now? It's been established since the OT that

A: You still have a physical presence in the moments of accelerating into hyperspace and decelerating from hyperspace, and

B: Ships can at any point physically ram into the bridge of a ship, destroying it. This happens in the OT when a disabled TIE fighter jets off accidentally into the bridge of a Star Destroyer.

So why did it take all the way until TLJ for anyone to do it? It seems to be something any military force in Star Wars should be aware of, so they must have their reasons to not. I don't really see how this scene opened the floodgates/retconned the past so much as it did a realistic thing that technically could've/should've been more common in the first place. Imo this isn't so much an issue with TLJ so much as it's been an issue since the beginning of hyperspace jumps.

The real answer as to why no one does it on a regular basis is that it's overtly complicated to pull off compared to just shooting at stuff, and that it doesn't do nearly as much damage as most people are trying to make it sound.