If the fight is immemorable and forgotten... that's more probably the fault of the DM than the system.
ANY fight of any length can be the greatest thing ever or a complete waste of time depending on how it is run. And after all... this is the reason to HAVE the additional levels of complexity. So that if BECMI 5E doesn't do it for you... you can add in the more complex stuff.
Ugh, pardon me while I go puke at the thought of BCEMI DDN.
See, that's what
really bugs me about DDN, it doesn't feel like Wizards is actually
trying to make a more unified edition that draws from all the things people liked in the past and eliminates most of the things people hated. It feels like Wizards is making a great big make-up edition, the edition that will say "We're sorry!" to all their past fans.
But this is why I hate saying fights should take X or Y amounts of time. Fights should take exactly as long as they take. Because there's absolutely, 100% NO reason to even
have a fight if there's no going to be some value in it. This is why MMOs have moved away from hallways filled with "trash" mobs to more boss-fight centric design. Why have a fight if for no other reason than to have a fight? It's a pointless waste of time.
Fights should serve a purpose, they're a gating mechanic, they make you use resources, they test your coordination, your raw power. If you walk into a room, crack a few kobold heads without expending any real effort and then walk into the next room, what was the point?
And the flip-side of "quick fights" means "deadly combat" and we shouldn't be using the
length of a fight as a measure of how deadly it is. Sure that kobold only has 10 health, but you only have 15 and he hits for avg 12 points per hit. I don't enjoy systems that value lucky dice rolls over everything else. Rolling dice is fun, but being at the whims of the dice and feeling like a random number generator has more control over your character than you do is not.
You're right that good fights can be quick, and good fights can also be long based on a lot of variables. THAT is what we should be emphasizing, GOOD fights, fights with meaning, fights that serve a purpose. I don't want the idea that appropriate-challenge enemies should not be a challenge, to get lost in the desire for "speed". Fewer fights will be more enjoyable with greater meaning and purpose than more fights with less.
....well dang that was longer than I expected.