Hussar
Legend
Different games might fare better with different approaches like that. In terms of 3.5, I've noticed there are definitely some standard magic items that are heavily implied to be assumed and thus become "regular" gear, but there are also a few more circumstantial items that fit the bill for something so nicely that I can definitely see giving them out as rewards if not for "skilled play" then for going on a quest or otherwise putting a lot of effort and resources towards getting.
On the topic of some player-driven stuff versus a DM's "preconceived notions," I was once in a group playing a cleric with the Air domain. The party was captured and basically turned into gladiators and crap. During one of the matches there was magical fog in the arena. Naturally, I had my cleric use Control Winds to move the fog off. The DM got this look on his face that plainly said he not only hadn't foreseen this, but he was pissed off and didn't like how I had "ruined" the encounter. Even when I pointed out that, according to the rules on various fog spells, a strong or severe wind would disperse the fog in one round and since the Control Winds spell lasted for 10 minutes per level and didn't need me concentrating on it unless I wanted to change it, the fog should disperse and wouldn't be coming back for a while the DM was like "No, the fog comes back immediately."
That's what I'd call a preconceived notion. I suspect [MENTION=22779]Hussar[/MENTION] would have at least been irate at that point (if not before since us getting captured was indeed BS) and probably even walked off by then. Luckily I didn't have to bother with that table for much longer because they stopped inviting me. At the time I was a bit dismayed, but now I realize the DM was full of himself and I dislike being around people with that kind of outlook.
Yeah, I'd finish out the session. But, yeah, that would likely be my last one. DM's that can't handle it when the player actually takes the time to read the rules shouldn't be DMing IMO.
To me, "No, the fog comes back immediately" is identical to, "The chamberlain puts his fingers in his ears", "The woman won't talk to you despite the fact that you look like the lovechild of Robert Redford and Sean Connery and have the voice of Barry White", "Everyone in the world knows exactly what a Rope Trick is and how to look for one, and, if they don't find it, have perfectly executed evacuation plans that completely clear out the habitation in under three hours, leaving behind nothing of value and no clue as to where they went." and on and on and on.