I'd have to be mostly in agreement with Aethon. With us hard-capped at 99 there's going to be a limit on the difficulty of regular content, and to some extent even on boss fights. SE learned a lesson a few years ago with parental outrage over the difficulty of AV, they are unlikely to revive THAT level of difficulty. So, to make the content entertaining they CAN'T make the gear much more powerful than it already is, because too much of the game is easy mode as it is. Hence side-grade since we are already at the easy-mode limit on most content.
and @Detlef, I read that quote too, but I got a different take on it. It sounded to me more like they are going to be extremely cautious on gear stats to prevent OP while still making something we might want, if only for situational use. He also said that he didn't want to shut out the casuals from end-game content, and making content that could only be beaten with multiple sets of Uber-gear swapping that is only from major difficulty and/or super grinds would likely do just that. It sounded to me like the goal was to make content that even casuals could beat, it would just take alot longer to work through it.
now, I'm not sure that's the way PLAYERS want them to go (some certainly do), but it seems like what we have...