Let me put it simply. The weapons that they designed in year 1 were higher tier than they should have began with. They made raid weapons with elemental damage with godlike perks in the first raid. They had guns like gally and thorn that were clearly broken. They didn't put infusion for year 1 weapons because they needed to essentially wipe the slate clean and start new because they had weapons that would never have been outclassed in year 2. Everyone would still be running around with their gallys their fate bringers their black hammers their fellow winters lie etc. This was needed to have more variety in weapon choice and not have such a small set of viable weapons. It sucks, I know I miss those weapons, but it was the only way they could make the game better for the future.