The pots are for the convenience and utility of the growers. Most aquatic plants are grown emerse in trays of water + nutrients in high humidity and strong light. With emerse growth there is no algae issue, the water can be nurient-loaded with no downside. The rockwool is a decent rooting medium and the pot make it easier to handly and ship.
But the rockwool can retain minerals and leech these into your tank, and the pot is un-needed and potentially restricting. Get rid of it and the rockwool. When you buy plants for your outdoor garden, do you leave those in the plastic pots? Nope.