I am not opposed to using anything, right hand or left hand or fingers or pick or instrument or effects or amps or direct boxes or eq or studio magic, anything to get a desired or yet-unimagined sound. Plectrum - pizzicato...? What ever is best for the player and gets the sound they are happy with.
As a kid, I started with fingers. Then getting into speed metal, I switched to pick. Couldn't keep up with the blurry wrists of Sadus guitarists, switched back to fingers. First or second demo of Sadus, realised in the studio that I still couldn't really keep up with their picking using fingers on bass. Beat myself about the head and neck area until I perfected speed with right hand. Recorded first Sadus album and smoked all my parts with flawless right hand speed technique (yeah right!). Stayed the course for many years perfecting right hand pizzicato style. Eventually realized that it had been a really long time since I tried pick. Now I bust out a pick every now and then for a desired effect on certain songs.
Use what ever gives you ultimate dexterity. Use what ever makes the right sound for you. Don't in fact copy the players who suck...please be imaginative, innovative and ever-so interesting. It's up to us to smash the standard of shit bass players - especially in metal. Crush the norm...get some balls...rise above and do something with intestinal fortitude that grabs people by the scrotum and sets a new standard in motion.
It's not OK to suck.
SDG