It has taken 20 plus years to get an air borne laser system into a C-130 with all of its cubage and weight carrying capability.
Into a fighter that hasn’t even into 3D mockup yet in 15 years. That’s some really good shit they have! Can I have some, please?
Like I said, the 15 years means that the prototypes are flying. At least airframe, engine and basic flight test avionics.
As to advanced weapons ... the aircraft could have built-in growth potential to absorb them down the road should they reach a targeted weight and power need.
Like how the Zumwalts are going to sea with the 155mm AGS, but have enough electrical generating capacity to backfit a railgun.