I'm not going to say the Triforce quest in WW because i really didn't mind that, WW was too much of a wonderful game for me to hate. Just looking at it makes me smile so playing it will get no negativity from me in terms of enjoyment. =]
This next task was technically optional, but the game would have been extremely tough without it, so I basically call this mandatory. Collecting fairies in the temples in MM. Especially without magic and enhanced defence, the game would be tough. I know this was an added challenge to the temples, but this was again annoying. I found the MM temples (other than the Woodfall) to be more challenging to begin with than OoT (other than the Water Temple) and adding the time limit (not a fan of time pressure and I'm someone who just can't play video games for more than at most 2 hours at once) and the fairies made them almost excruciating.
Especially that damn Snowhead temple. The fairies were so out of the way and the temple was long and miserable, my least favorite of all time. Let's just say the temple took me many tries and I had to do the fairy quest separately (remember I am not a hardcore gamer, most things are tougher for me to being with!) I would have rather had a 5th tough temple, rather than getting all those fairies.