I've played a lot of Mario Kart 8 on the Wii U and always thought that having only one item slot was actually an improvement to the series. I was really glad they did it.
It makes it harder to stay in first place. When you get a coin now you actually have a problem. In older Mario Karts you would have some sort of backup. Now it's a real risk letting go of your shell. It often happened that when the first player manages to get a little ahead he is almost impossible to get back to. But not in Mario Kart 8.
Having less stockpile in general makes the game more situational and a little less chaotic.
Do you think two item slots are better?
Discussion started at here by heilerschlampe