I can at least kind of understand why customization might not have been as good in Tag 2. They pushed the game out much faster than Tekken 6, they had almost 20 more characters to manage, and they had to get 4 fighters on screen at once (and in game, ready to switch in and out), all while working with the same limited memory.
But with Tekken 7, they've been taking even longer to finish the game than Tekken 6, with fewer characters to make items for, in only 1v1 fights (only two characters need to be loaded), and on considerably more powerful hardware.
So what the hell?