I think it's more like the parts of Magic where Harry is actually talented is in crafting stuff, rathen then his skill at illusions growing- Little Chicago was impressive by Bob's standards after all, and his potions have always been stupid OP, which is why Jim wrote them out of the series.
Since Harry has his lab back now, I assume potions are also back. They are not stupid, chemistry is one of the primary areas of study of wizards historically, let's not forget it was a potion that allowed Harry and company to sneak in and spring Thomas.
Crafting stuff is another talent that shouldn't be pooh, poohed.. Wizards also need their "gadgets," you might consider a staff a gadget that all wizards seem to carry... Rashid gave up his eye for a very important gadget... Not sure about the eye, but someone had to craft the staffs that they carry, how well it is done is very important.
The problem is he stopped developing that natural affinity because 'hur-dur reul Wizzard dun use silly toyzzz' So Harry is basically Molly if she decided to focus on Evocation instead of illusions.
Because like I said, he's an idiot.
Really, well, Harry did use a very serious toy in Battle Ground, the Spear, the thing is he knew enough to keep it under wraps until he needed to use it, not the actions of an idiot... He matched his will against a Titan, no toys there, just his will. If Harry was an idiot, he never would have gained access to those very important and powerful toys he found in the vault of Hades back in Skin Game.