The only loot tables that have been affected are those for NPC battleships, and the only changes made to these loot tables are that meta 0 items have been replaced by metal scraps (and navy tags where applicable). This affects Battleships drops regardless of where they are found in the game, missions, DED complexes or exploration sites or belts. In general, the rate of meta 1-4, faction, officer and deadspace drops hasn't changed. (Although cruiser and battleship sized afterburners and microwarpdrives are now much more common drops for some reason.)
The purpose of these changes was to make mining the primary source of minerals in the game. Meta 1 or better items were never a signficant source of minerals.
Ninja salvaging and salvaging in general hasn't changed. Before the expansion, no one cared if you salvaged mission generic wrecks (left by non-faction ships like mercenaries) because their salvage wasn't and isn't worth much. Most ninja salvagers wouldn't bother anyways; they'd just go and find a better mission to salvage instead. On the other hand, if you ninja salvage a large Angel or Sansha wreck, you're just as likely to get tears as before.
The fix that now favours sending mission runners to low population systems rather than high population systems probably has had a bigger impact on mission runners.