Gorgon Zee
Hero
A good FATE player calls on his character aspects as often as possible and for as flimsy of reasons as possible. You are always on the lookout for tagging every action because if you can tag an action, that adjusts the math so much in your favor that if you don't you almost certainly will fail. As such, what you typically see in a game of FATE is frantically leveraging the Aspect system for straight forward gamist reasons with the result that FATE's primary aesthetic of play ends up not being Nar, but gamist. People compel, call, tag and so forth primarily for "Step on Up" reasons and aesthetics related to Challenge and Self-Affirmation, and not for reasons pertaining to Story. By turning the character into a mechanic that directly relates to success all the time, it turns all the considerations about playing your character into weighing not the character but the need for mechanical success. It's actively undermining its own intentions with the design in the same way that social systems that mimic combat systems in order to make social interaction a pillar of the game are inadvertently undermining the RP that they want to encourage.
Certainly in combat, people look to use their aspects and abilities as much as possible to gain victory, and if they don't try to do so, they are unlikely to. But that's just a standard of play, isn't it? I mean, if I'm playing a rogue in D&D, I'm always looking for flank. My spell-casters are always looking for the right spell, or an opponent vulnerability.
I suppose you were hoping that Fate would be different, that you wouldn't think about trying to gain an advantage in combat, and that every turn you'd just roll dice, add your skill and hope you exceed the target? And that your other character qualities would only be useful for roleplaying? Or is it that you want a clear distinction between gamist and narrative? I'm uncertain about what you are looking for I guess.
For me, the big reason to play Fate is that the gamist and narrative elements work together. In other systems, in combat, I have to choose -- does my pirate swing on the chandeliers and attack (a narrative choice which in most systems is less effective than using my best power) or does he just do his usual thing and make a called-shot rapier thrust to the eye, using feats X and Y to reduce the penalty to -4 and using his class power to get a re-roll? If you have a generous GM they can arbitrarily add bonuses to make the narrative thing actually effective, but ... that's exactly what Fate does!
Fate allows you to do both, and makes it not only OK, but effective. As you point out, if you do the boring thing you simply don't succeed -- you must do a narrative thing to get gamist success; this contrasts to other systems where you must do gamist things to get gamist results.
I've played and run an awful lot of Fate, and for me, the fun part is that there ISN'T a purely gamist way to succeed at challenges, as you seem to want. I'm running a deadlands game, and people are pretty consistent now in how they approach combat (after 20+ sessions). I don't see much variation. I play a 22nd level D&D4E character and I will absolutely try and use the same power every time if I can. That doesn't happen with Fate because to get a gamist advantage, you must use a narrative feature. So sure, I can tag my generic "I hate not to be the best" to get a +2 to my swordsmanship -- but I could equally well tag the chandeliers aspect for the same bonus, so even with a pretty limited GM I can blend gamist and narrative.
A good GM will incentivize the players, of course. Add a free invoke the chandeliers, and immediately you have a situation where it is better to the narratively fun thing than do the boring thing.
The same is true outside of combat. If we want to persuade the king to lend me a ship, then in most systems you go through the party's skill lists and guess what the king's opposition level will be and then decide if the gamistly optimized bard will use diplomacy, or the gamistly optimized thug will use intimidate. In Fate you are way more likely to choose options that are both effective and narrative. You take the fact that you are a "survivor of the wars against the Gree" and, wanting the gamist bonus, spin a narrative story. For me, this is a good thing -- THAT is the core of Fate's challenge mechanics; not allowing players simply to be boring to get the bonus, but making them inject narrative to do so.
Now there are lots of reasons not to like Fate -- plenty of people hate the meta-currency thing, sure. The fact that big combats often consist of piling on advantages and one big hit. The need to make stuff up as you go. But I think that saying you think Fate would be better if it didn't tie together mechanics to succeed in challenges with narrative elements is all off the mark.
Maybe I'm wrong, but it seems like you would prefer a game that has completely separate systems for challenge resolution and story? If so, I enjoy D&D4E for being 100% challenge mechanics and 100% freeform roleplaying; and also DramaSystem for being 90% about the story (I'm counting drama resolution mechanics as story here) and in practice I've never even used the challenge mechanics -- last time I tried, the table just said "can we just a assume we win?" and so they did.