While I applaud your creative use of the poll options by turning it into a graphical rating system (seriously, I didn't even know you could put emoticons in there), I think that your poll would have been much clearer and more useful had you used verbal descriptions of what each option meant, rather than increasing numbers of fairies.
Anyway, that aside, I do not feel that the child dungeons were a waste of time. You have to remember that for many people, Ocarina of Time was their first Zelda game. As such, the initial dungeons are more like a tutorial. Thrusting someone into the Forest Temple right away, with no clue what they were doing, would have been horrible game design in my opinion.
In fact, the child dungeons do increase in difficulty as time goes on. In the Deku Tree, you learn about the most basic mechanics, lighting torches, rolling, opening doors, burning away webs, etc. In Dodongo's Cavern, you learn about how to deal with fire-based enemies, bombs, attacking weak points, looking for hidden stuff, and slightly more complex puzzle solving.
In Jabu-Jabu's Belly... that's when things get a little more complex. You get punished with damage for attacking enemies at the wrong time, you have to identify strange looking switches, figure out the connection between the barriers and the tentacles, beat a timed room with several bubbles, and beat a boss that requires constant movement and a strategy. You also have to carry Ruto around to help you reach your goals, which is a new twist. I would argue that this dungeon is as hard or harder than any Adult dungeon, because of the innovative use of the boomerang puzzles and the need to carry Ruto around to use as a weight. No other dungeon in the game requires those things.