Piccolo and Gohan have held minimum roles in the new iteration of DBZ and this isn’t pleasing to a lot of fans. Now with the “Tournament of Power” story arc on the way the training of Gohan is more important than ever because. The show really needs to revive the Piccolo/Gohan relationship and perhaps have them train in the hyperbolic time chamber together. A few fight scenes and a power boost for both characters would really add some much needed diversity in the DBZ line-up.
The Tournament of Power will be a battle Royale, so the Z-fighters will have to rely on tactics and strategy to win. Piccolo over the years has proven to be the smartest fighter on the team, especially after he merged with Kami. He has a different array of sneaky attacks that will confuse enemies and likely cause a ring-out scenario. This tournament isn’t about power levels and transformations its about fighting IQ.
Dragonball Ball Super has been very saiyan heavy and this hurts the show long term. It is only so many story arcs for Goku and Vegeta, especially since they reached Super-Saiyan Blue status. They have left the other fighters so far behind that they seem out of place in the show. So it forces the show to do these plot-hole “power boosts”, like they did in the Black Goku saga with Trunks. They are forced to make the characters stronger for them to be involved--even if it doesn't add up story wise.