The goku piccolo special beam canon is from before the line was canceled, it was catering to japan who prefer heroes, and its freakin goku. Goku needs no hyping and goku hyped piccolo.
It's about hether it NEEDS hype. At sdcc the over 9000 display was a massive "look at what we can do" capitalising on the meme to CREATE hype, because there was little for a line that had been cancelled. Also action figure collectors wanna see action figures, that simple.that's why they don't mix zeroes and articulated in displays.
Now I agree wirh you regarding what tamashii shouldve done from a fan pov, but from their pov most displays in conjunction with where they were setup and WHEN, is pretty consistent with the factor of whether thy need hyping, at that place, at that time.
The line has taken off in the west and now theyre retrying to hype it in japan, thats why they get the bigger displays. Ssj4 goku was cut for now because of DBS, that clear. Ssj4 goku isn't needed right now hypewise, because the west is hooked anyway and DBS came inbetween. Shenron is just a nasty tease but they used him in japan. They use protos to hype up their products. That seems to be thir buiness strategy. It might suck and/or seem inconsistent from our pov, but from a company with a location based hype strategy, which tamashii seems to have, it actually isn't.
Me and bardoon and few others I think called no new reveals at sdcc and we were right. Why? Because hype: they go by hype building. Sdcc needed no hype building. Sdcc 2015 goku sales is proof of that. It's clear tamashii doesn't do **** unless it's needed for hype = for sales.
Nowwhat my personal opinion of all this is as a fan I've made clear (too) many times before, but from a hype strategy pov tamashii isn't acting entirely illogical at all.
I mean I could spend that kind of cash on a Hot Toys figure which I also collect and they're far heavier, sturdier and bigger 
