I agree that without fandom DJ probably wouldn't have such a reputation as being 'weak' or 'needy.' But I don't think there's too much of a deal about it. Fanfic is by it's very nature free for whatever interpretation of the show you care to give, being extreme showing D/J D/S J/S J/J T/S... there are so many relationship combinations in fandom which cannot all be canon anyway.. but could theoretically I suppose be possible.
When you have so many people just writing
(and a lot of them really are raw newbies and didn't go thinking 'What would Jack do/say/think here' they put what they WANT him to do/say/think/feel/be or what the storyline demands. [I do this and cop-out with it not being THEM...]) there just isn't a consensus and never will be in fanfic. The characters differ according to the writer a great deal too... in one H/C fic Daniel can be a pathetic wimp needing saving AGAIN or he can be something USED (sometimes by the bad guys or sometimes by just the writer) to get to his team. When it's taken to the 'Why did I let them do that to Daniel' or 'Why is it always him...' I feel it is a diffeent matter. But then I will and have read stories in all the categories/genres whatever... and sometimes I can stomach this type or that and sometimes I can't... All depending.
People don't always try and stick true to the show and the fact sometimes doesn't even occur to people that you can, but that doesn't make it any less a good story. For those people who like that kinda thing... sure!
As to the WHY certain people write certain ways... Well. God knows why I have my own peculiarities but I do.
I sure as hell do not have a lot of the experience of a lot of the people out there. My only military experience is the pathetic 2 yrs I spent in the ACF which practically means I know how to strip clean and assemble an LSW and I can throw a few handsignals in... I don't know how much it helped. A lot of peopel don't even have the rudimentaries of military style that I have and I wonder how much different my writing would have been had I not had it, aside from lacking a few terms maybe which end up the Anglicised ones anyway. I so easily could write differently and know this. The first peopel I came into contact with and read stories of in SG fanfic- before finding Helio even- all belong to the H/C list (not mentioning names) and I was told by oen after reading my first one that I probably 'belonged to H/C' even though that tentative attempt ended up whumping Jack and Sam mainly, having the hint bewteen them and some inkling of a strong Jack/Daniel friendship. The next one was probably a little more influenced, but I stil lended up whumping Jack and having Daniel do his best to help out...
*I* don't even knwo what I am or what I write or why. And I think about it too much and stil ldon't know. After being told that writing angst was bad... that threw me... oh and many people say I don't even do H/C but A/A and then others say I DO do angst and then.... So I just don't bother anymore. it's not like there's a huge problem if I go out of canon, or the characters arent' WHOLLY sticking to themselves... It's not like I'm getting paid for it!
So I don't think that labels realyl work too well. There are some absolutely dire H/C out there, alongside some really great ones. One of my favourites and one of the earliest I read is H/C but not the tried and tested kind... a lot Angsty and it did make me cry when i read it. But there are conventions even in shipper/het... really the best stories aren't classifiable ones. They may have elements of all of them in them.. but are just good stories, regardless of canon or not.
And as for 'does Daniel ask to be whumped?' I reckon no more than the next man. Just look at Teal'c... wouldn't he be asking for it by always being assumed he can cope? What if sometime he couldn't? Wouldn't that slight vulnerability be just as easy to play on? It's stereotyping is all. And I've probably made no sense but hey. I'm not feelign well so Can I Be Excused Miss?