Also a new RS3 player here, moved from OSRS (just waiting for new content).

OSRS is in desparate need of item sinks. Prices are dropping so fast and some rare drops from end game content are worth less than the standard loot you'd get. Rigour, probably the best ranged dps increase, is only 14m now. It was upwards of 100m in the past (from what I know, I bought mine at 58m).

CoX is already worse money than hydra, vorkath and zulrah. The only exception is if you hit a tbow. ToB isn't close to falling that low yet, but it's slowly creeping there. Something like invention would definitely be beneficial to OSRS to keep the harder content more profitable than the easy consistent money printers.