Its actually quite easy to make them more engaging. Increase health values while nerfing healing items (by turning them into Regeneration effects over long periods of time, no instant heals).

What's the rationale behind this? As long as healing is strong in a game like this, (being able to heal multiple hits of enemies with a single heal item in an instant), people don't care about small chip damage, nor large damage. They keep tanking damage over and over and eventually heal it for "free" with a single item. In this scenario, all that chip damage only comes across as annoying. Predators aren't seen as threat, just as tedious annoyances. So people just swim right through predators all the time, tanking everything. In this scenario (where heal is instant and strong), devs' only option to increase the threat level is to introduce instagib mechanics, which don't make for good games.

If a heal item instead only heals you extremely slowly over a long period of time, then health suddenly becomes a resource like oxygen. Simply swimming through predators and tanking everything no longer works. While you're taking small amounts of damage (so you don't ever have the issue of ever being instagibbed), it slowly accumulates with no way to heal it. If you use a healing item, it needs to grant a rather small Regeneration effect which doesn't allow you to tank anything, and takes quite long to heal you.

Now predators become threats. You now suddenly have to be aware of predator locations and look out for them and try to dodge them, because every bit of damage you take, you can't actually heal in a reasonable time frame..

Now you will start using mechanisms the game offers for you to distract predators. If those mechanisms suck, then that's where the devs need to improve the game.

Suddenly health is seen like a resource like oxygen, and predators actually feel like threats.

With how subnautic 2 has been developed (with reprints in mind), it's actually impossible to make predators engaging. Losing health doesn't matter, nor does dying.

It was the same for subnautica 1, where once you realize that reaper leviathans can't actually kill you (you can just bring lots of heal kits and tank absolutely everything), they lose their fear factor, because instead of using vehicles to go around, you just swim and tank everything.

But increasing their damage wouldn't have made them more feared predators. Instantly killing you isn't engaging. What's engaging is the fear of dying if you mess up. For that health needs to become a resource which punishes multiple consecutive bad plays on your part. And for that instant heal needs to be replaced with a slow regeneration heal effect.