They use Chinese American kids as example, argued that lots of these kids hate to learning Chinese characters, and their English reading and writing skill developed way faster and easier than their Chinese. I would not argue this part, but I personally found this idea of pinyinizing Chinese not so appealing because, first of all, I do not believe that Chinese writing/reading skill are that hard to learn, and I either don't believe English is an overall easier language than Chinese. I understand that Chinese writing system maybe hard to learn only during the beginning period, because you probably do need to memorize all those characters "from scratch" - because there is no connection between writing and pronunciation. However, as long as 3 or 4 (even just 2 or 3) thousands characters were mastered, the rest of Chinese language learning becomes a piece of cake - you literally don't need to make much effort at all. So, these first a few thousands characters really become a lifetime saver. The reason for this is because most of Chinese words were composed by these basic characters, so if you recognize them well, you would have no problem to know most "compound words", which are the most of Chinese words made of.
I believe that a high school graduate Chinese student should have no problem to understand any Chinese documents, include fictions, magazines, and some professional documents as well, because they usually handle much more than 3 or 4 thousands characters. That's why there is no Chinese reading and writing test in graduate school entry exam designed for all applicants in Chinese universities, but on the contrary, in United States, GRE is for all students its English language part is not only difficult to foreigners, but also lots of American students.
I personally found English is hard to learn, especially its vocabulary part. Some people (in the forum) argued that English also has lots of roots, prefix & suffix, but I found roots, or prefixes work in a very different way from Chinese characters. In Chinese, you have to learn those basic characters before you go anywhere, which means these characters are basic elements on which the whole language based, but in English, understanding roots, pre or suffix, works only like "assistants", which helps a lot, but is not a "must" for beginners. So after all, memorizing words is still a major labor work for learning English, especially for those who use this language as the second language.
The second reason that I don't think pinyinzing Chinese writing system is a good idea is that Chinese language has a n incredibly huge amount of homophone characters. This makes way to difficult to distinguish words just by pinyin (or alphabets). And it is because of this shortcoming, Chinese writing system actually serves as a major complement, because of its rich variation in its visual form. I believe that Chinese characters were invented for reasons - the separate individual syllable were best to be represented by each individual character. I also realized that alphabetic languages are more vocal or acoustical - so they sound beautiful (and alphabetic system naturally became the best way to record these languages, and I believe this was why western cultures all preferred and adopted this system over Sumerian's cuneiform writing system back thousands years ago); Character based language such as Chinese are more "visual" - they looks beautiful! Personally I believe, that throwing away Chinese characters, Chinese as a language would totally lose its "charm".
I think many people would agree, that the reason that English is widely used and becomes almost as "world language" is because of its cultural influence, not because of its language facility. If so, Spanish should be the most used language, because it's easy to learn. (I heard this and hope what I heard is true)
Well, I hope those linguists who propose alphabetic system would invent some pinyinized Chinese script system, and let history speaks for itself.*
*Actually I heard they tried already but didn't succeed.