In Skyrim, it was boring as hell to complete quests because they never really offered me anything.
I mean, I want a level cap at some point but quests not giving exp? It gave me no reason to try and complete them.
If a quest was about "Heal soldiers attacking X they need a priest!" then the purpose o the quest would be to get my Restoration skill up.
But it never felt like that in Skyrim, I was sent down to dungeons all the time.
The dungeons became repetitive, the loot was standard and the quest rewards were utter crap.
I had no incentive to continue, no motivation to do anything, I had the armor I wanted, I had the axe I wanted, what else is there for me to do?
Experience points is a great way to reward players for doing things, and I mean anything, cause even if I get experience points for hacking a computer with no plans on raising Science any higher then I can use the skill points I get at level up for things I do want to increase.
But quest in particular, in Skyrim, I don't really feel like doing anything.
The quests have mostly crap writing and just send me down to more dungeons and I don't get items I need or want and to top it off I don't even get any experience points.
Even if I got a crap weapon I don't need in a Fallout quest at least I would get experience points to make it worth while, and of course good writing... And not being sent down a dungeon...
Also, I like freedom.
In Fallout I have a great sense of freedom as I know I can do whatever I want and get the character to be what I wrote him out to be.
But in Skyrim I feel this pressure on me, that the only way for me to get the character I wrote him/her out to be is through forcing myself through hours of gameplay in a linear fashion.
Skyrim, ironically, felt linear with character progression, in order to get Speech up I had to do X.
While in Fallout, I have freedom with character progression, so that if I want to get speech up then I can, I don't have to search for characters to dialogue my way through and I don't have to sell items one by one for Barter. I simply do things, level up, and take what I want.
Learn by doing is more realistic on paper, but ultimately, it's a game and it's meant to entertain you and let you have fun, and too much realism isn't fun. At least not for me.