I have seen high population servers with strong PuG communities that was doing 4-5 bosses in vaults before HoF was released. The first week there was PuGs that downed three bosses. MSV was more mechanics oriented until the last two bosses. The third boss required 40k DPS while experienced raiders was already pulling 50k DPS. Then you have Terrace which mechanically is among the easiest raid with PuGs even doing the elite mode and is more about performance with the last boss being almost exclusively a performance test which is understandable for an end boss like the T11 bosses was like.
The performance tuning is going to be more forgiving next tier for normal mode. Players will still have to dodge fire though and I like that. Mechanics should mean something or otherwise why have them at all.
I see gems, enchants, and reforging as common practice when it comes to normal modes. Even in WotLK it was not uncommon to see players get things enchanted and gemmed during a raid or a player just not using a new item because they know it will not be better without the enchants and gems. A lot of players do flask as well. If they use pots I have no clue. I really cannot fathom not doing these things in normal mode unless I am doing a raid that is farmed or old.
Most of the posters I saw complaining about Cata raiding being hard did not even clear ICC and I even spotted those who did not clear Naxx with a lot of 8-10 bosses downed. Frankly WotLK raiding was too hard for them as well. These players even forgot about the one shot mechanics in WotLK launch heroics and the multitude of complaints about multi hour long heroic runs. Obviously most of these posters in WotLK was laughed at because we came from BC where most of the mechanics was nothing new to a large portion of the player base and was not cry babies that rage quiet after a wipe.