Self-infliction will never be affected by resistance; the rate at which you get fire/cursed is entirely down to the weapon, and utterly ignores your resistance. Your resistance affects the status itself *once you receive it*. It's like when an enemy afflicts you with something; your resistance won't prevent you getting it, just lessen the effects.

Status trinkets do get used, they're considered "useless" for two reasons:
a/ On their own, they're generally not nearly high enough to do enough to merit having them. You'd typically need to have armour/UVs with the resistances as well to clock it up, but after a certain point that tends to make the trinket a redundant bonus
b/ Other PvP trinkets tend to outshine them outright, since the game is generally more offence based, encouraging you to take the "kill them faster" trinkets over the survival ones.

However, that's not to say they're not worth it. It entirely depends on your gear. If your preferred gear has no curse resistance and you spam GF a lot, then two trinkets will do more good than harm. Slap a curse UV on with that and you're golden.
However if you're using specific curse resistance armour, then the comparitive won't make the trinkets high enough value; that is to say, that not wearing them and wearing them won't make enough difference anymore, since the bulk of your resistance will come from your armour.
Even then, you might prefer the extra resistance over krogmo trinkets.

Or simply not be able to afford krogmo's. It's situational/personal preference, really.