1) Any item is effective against almost any enemy. There are multiple ways to run into an encounter; you can leave bombs at just the right moment, snipe them from afar with the bow, or even slap them around with the whip though it has no real usage. Skyward Sword hands down has the most effective items of the series.
2) SS' controls are absolutely flawless. They work 101% of the time; they work as planned. If you run into any problems, it is due to the PLAYER, not the GAME.
A) if you seriously say the bow is more useful in combat in SS than it was than, say, WW, I have no idea what you're smoking. The forced first person view combined with the motion controls make it unusable in combat. Objectively those very same motion controls make using those items not as reliable as using the sword. Again, in past games, they worked as soon as you pressed the button, but in SS, you have to worry about how fast you are at pulling off the motion to use the item, whether it be too fast or too slow, which depending on the situation could negate you being able to use it all together, so why would you bother with that, when you have a sword that can swing in all 8 directions?
They knew that, so they made most of the enemies literally REQUIRE the sword to be used to kill some fodder and bossess because they block in certain directions.
That's a personal experience not an overall experience. We're talking objectively remember? Not everyone had a perfect experience with the WM+, including me. Sometimes I would quickly move the sword to the right then slash, and it read that movement as a slash in the direction i already had the sword, I then got hit by the enemy. I got hurt because the controls weren't able to keep up with me. That's bad even from a Hack and Slash game design philosophy.
Again, they may work ALOT of the time, but that simply isn't good enough, especially seeing how SS is VERY combat based.