Just today, I read an article about the influence of the computer on the chinese language. I can agree with some of the points of the author, but think that the difficulty of using a method like Wubi is generally overstated. CangJie is more difficult, but in contrast to spoken language, they both have the very valuable property of not changing according to dialect, region or time. The speedups a user of predictive input gains, are also avialable to users of handwriting or structure-based input methods, but the input speed should be excellent at 150 words, achievable in Wubi, or the 200 words achievable in CangJie. On top of predictive input and much less guesswork that makes the phonetic input methods slow, the structure-based input methods sport phrase books and rules for having hortcuts to type several characters in one go. And while I have seen every undergrad student using only PinYin or ZhuYin, every PhD student that I have met so far, has switched to Wubi, simply for the massive speed increase.
However, I am unconvinced about the notion that writing Chinese is slower than English:
If you can type 150 chinese characters per minute, that amounts to roughly 50 words per minute if you subtract particles and composita, as many chinese words have only one or two characters. Now, imagine how fast you'd have to type to achieve similar speed in English: If the average English word has four characters, which is probably not enough, you'd have to type at 600 characters per minute to achieve similar results, and then you have spacing, too, which does not exist in Chinese. I also hold that the structure-based input methods at least help you memorize the graphic elements of the characters, thus being closer to hand-writing than phonetic input methods. With the composition rules and phrase books, you end up usually having one to three key strokes to produce a chinese character. In summary, I think it is not easy to say whether English or Chinese can be typed faster.
Unfortunately, my own experience with Chinese input is limited to PinYin and Wubi, and as far as the steep learning curve goes, the principles of Wubi can be explained in probably one or three hours, and after that, it takes two weeks of practice to achieve some fluency. Not a big invest in comparison to learning Chinese in the first place, or the waste to be accrued over time using an inferiour method. I guess it is mostly the psychological barrier, possibly combined with unsophisticated didactics that contribute to the perception that these methods are hard.