Sooo...take that thought one step further. Obviously an auto-win (100%) isn't fun for you, but neither is an auto-TPK (0%). What odds make for the epic fight?
My point is that while the extremes are often problematic, the odds aren't what make for the epic fight. The odds of success don't really speak to how much or what kind of work has to get done before you achieve success.
Last week, I ran a session wherein the players honestly were bound to win. But there was an airship, acid guns, and an undead slippery-fish of a mad scientist involved. There wasn't much I could do within the rules to keep this guy from shuffling off to Boot Hill, but I could prolong his (un)life so the action was cool. The players ended by describing the encounter as "Awesome!"
For a typical encounter, how do you like your odds? My first poll: I have no idea how to do this, so forgive me if I frak it up.
Edit: Allow me to rephrase: For the most fun encounters, what constitutes the most fun odds of success?
I would totally agree with you that there is more to an epic fight than odds, and that those things (evocative descriptions, imagination, etc.) are critical, but surely seeing that the odds are against you and yet somehow pulling it off makes it that more fun, right?

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.