I understand that Riot wants to keep RNG a large element of TFT as a way to keep every game different, but I do feel like there is little you can do about having sub optimal luck ,or , being ahead and only receiving low priority items on carousel (which has become more common since they reduced carousel items from 10 > 9). I recently had a game where I inadvertently ended up with 3 Ionic Sparks, not an item I'd want on any carry.
So, with respect to their decision to keep RNG prominent, my suggestion: Allow players to discard 2 raw items in order to gain any 1 random completed item _except_ the sum of the items that they had discarded. Using the Ionic Spark as an example, I'd discard the Needlessly and the Cloak in order to gain any completed item that isn't an Ionic Spark. Only raw materials can be discarded so there's no going back. I feel like this change would only make for a more positive experience.