Are you sure it didn't get shot down? After all, they are flimsy.
But if we are going to be splitting hairs to this ridiculous level, i am obviously talking about collector limpets. if the came can make that distinction, so can you.
Why should your limpets be invulnerable and not mine?
I can see your distinction. It is wrong.
I read your OP as "I want things made easier."
And I mean it's pretty hard to argue against how I'm reading that I suspect.
You said it yourself anyway. The limpets are cheap. Very cheap. You can pay for for a month's supply simply by passing through a system you've never visited yet thanks to exploration data selling.
You can even make new limpets on the fly thanks to synthesis.
The inconvenience of having a limpet occasionally crash into a rock is pretty much the only challenge miners face.
Also, after a big mug of coffee and thinking about this thread over a bacon sandwich, I realised that there may very be a critical flaw in your idea. A flaw that means should limpets be made invulnerable, (they shouldn't and probably won't), then you may often find yourself completely unable to use your collector at all!
Let me explain. The issue with limpets is not they are easily destroyed. It's bad AI. Here's the thing... If a limpet is indestructible and it gets stuck on a rock, which is what would happen when it inevitably collides... That limpet becomes dead weight. And you can't get rid of it. Now you have to wait 12 minutes to replace it.
They are quite literally disposable.
One final thing.
The limpets you use as a miner are exactly the same as what I use as a pirate. The only difference is the software they are coded with.
Physically they are identical as they are all purpose drones.
If yours are invincible, why aren't mine?
This suggestion of yours is, in my opinion, rather flawed and, as I said, this does all sound to me like a desire to have an already easy activity made easier.
Frankly this game needs more challenge, not less. Sticking to the status quo is agreeable, I suppose.