Can't say it better. They had to up up up the difficulty because of titanforged + legendaries so it doesn't feel like it's a pushover.I think the problem Legion content tuning is going to face is the power creep in the player base due to how gearing works.
In the past EN would have been the entry level raid where you could go in with heroic gear and some crafted stuff and take down on a heroic level. Or at least clear on normal and then start on heroic depending on guild skill level. But EN people were going in at 850-860 on the first day and the gear you were rewarded was 865 in heroic.
(I am excluding mythic raids from the example but its there if you want to math it out yourself).
Again, in the past your heavily grinding / lucky players would have been around 855-865 by the time Trails opened. But in Legion that number is already 880-890 and with multiple legendaries. So to not make Trails a total push over they had to tune that content expecting even average raid teams to have several if not many or even all players in that range of gear. So people following a traditional gearing and progression path are being left behind and in a much weaker state than in the past.
This will likely continue fort he whole life span of Legion.
So to really progress in content in Legion it is going to take a lot of content grinding which at this point shouldn't be a total shock to any one that has been playing this game or fallowing it closely.