You can blame the current meta for this, it's quite harsh on resistance builds due to the high number of high damage weapons everyone is using.

After another batch of weapon tweaks, the meta will change again and maybe then resistance builds will be useful once again.

Resistance is NOT so useless. Assuming there is no Resistance to Zero pads on the field (They should not exist at all), Having a lot of resistance as a heat mech will dramatically increase your survivability.

Also, stop using Diamond Shell. That thing is garbage now.

This^

There are huge problems with resistance right now(mainly with diamond shell, god mode and pads). But that's different from it being useless... lol