Well I think hulks tanks are fine if properly fit. I can easily have a 20k unheated tank on my hulk plus I also keep security with the hulk too. I mine in 0.0 in alliance space and there is A LOT of tools at your disposal to stop people trying to pop your miners. Intel channels standing fleets and belt security. These measures alone will stop all but the large blobs (and at that point you just safe up since their usually spotted in intel) or the occasional logoffskie attempt. And like others have said the hulk is a industrial ship designed to mine ore not engage in combat. Even in real life militarys logistics and transport is closely guarded. Going out to mine alone (especially in empire) you're taking a risk and since RoE in empire are crap its a breeding ground for griefers. Properly fit your hulk don't just think about max yield. A damage control adds a lot of ehp. Being in a fleet to adds leadership bonuses and possible gang links. At the end of the day EVE Online was met to be a group activity not a solo effort.

Quite irrelevant.

The point is, they're both the same kind of ship: a non-combat industrial-type ship meant for one thing and one thing only (and, just to repeat that: it's not combat). You can still squeeze 30k EHP out of a Hulk, and that's fairly respectable for what it is and what it's supposed to be doing.