"there has always been a speaker" it says in the lore, and it heavily implies its always been the same one, so we likely have to eradicate him at some point. i still can't tell if the traveler itself is evil but it definitely did bring the darkness or whatever it is with it to every planet and culture its ever came across, and the mars mission people were scared of what it would do if it came to earth and did there what its done everywhere else, which most would think means they were scared it would terraform earth and we may not be able to inhabit earth anymore, but there seemed to be alot more to it then that when i read it, like they were referring to something else more menacing either the darkness that follows the traveler around or how it leaves everyone and abandons them at some point, etc. and honestly alot of the base game story seemed to indicate that we really were fighting for the opposite of what we thought we were. so far the hive seem evil, the vex might be good, some fallen might be good, the exo could go either way even though they currently helping us the lore and announcements about their creation says they are all intended to be sinister thus evil potentially, the cabal just are warlike brutes that want to take over everything, and the traveller and speaker both seem evil in alot of respects thus far.