There was a lot more streamlining than you might think. I mean, the old DQ games didn't even have an interact button. You had to go into a menu and choose 'talk'. Also, everything was renamed in the now iconic 'pun' style that DQ is known for. Of the DS Dragon Quests, 4 is my favorite. I love how the DQ games always start out by giving you these little quests that seemingly don't intersect, but then they always start to about halfway through. They're almost like books of short stories that happen to have an overarching plot.
But FF6 just had so much there. The world was the most unique and fully realized of the FF games up to that point. Moment to moment, the story and world was just better than the rest. It did use a lame way of making itself longer, by having you reclaim all of the characters again, but it was so open. It was almost the inverse of the Dragon Quest trope, where instead of starting you out with small stories, FFVI had the game's second half do that. You didn't even have to get any of them back except for 4 of them, which I actually did a long time ago. Maybe a contrivance, but it fleshed out the characters' backstories. It was also so open to powerleveling, which may be weak for some people, but I liked that every character could learn every spell, and you could basically form the party that you wanted to have.
FFIV was good, but I'm so sick of it. I think I've played it at least 20 times on all kinds of platforms. V was really hard for me to get into. I liked the job system, but the story bored me, and it was very anti-climactic. The only other thing I remember enjoying was that the last dungeon had like 12 bosses in it.
There's an SNES remake of Dragon Quest III that uses the "engine" from the SNES DQVI that you should check out. A lot of people consider DQIII to be the best, and I don't really agree, but it is a great remake.