Story mode in raids?
Your best bet is to put a listing in the lfg asking for someone to open a completed instance for you (i do this periodically for people, so you could send me a pm sometime and I can open one up), then run through and read all the journals, and talk to the pact prisoners at the end. There isn’t really any other story in the instance, but you can look up lines of dialogue on the wiki for stuff that gets said during the fight.
As for a story mode, I really don’t see the need at the moment, because there is so little story to begin with, and you can experience all that story by entering a completed instance, so it’s probably not worth the development time. If future raids have more links to lore and w/e, maybe, but even then, I think the idea behind the raids is for them to be endgame, and something to strive or work towards, so it may not ever happen.
Anet has not mentioned about any plans to include easy mode for raids. Some sort of difficulty nerf may happen in the future ofc, as has happened to all content.
I expect there to be huge gap between players who do raids every day (week?) and find them too easy and players who try them once, find them too difficult and never return there. Its fairly pointless to throw huge resources into content that only fraction of playerbase can enjoy.
Oh what would I give for 5 man raids…