I was more pointing out the complicated words part. I did not have a clue what that limnology thing was, but looking at the kanji 湖沼学 i immediately knew.
And I am not a native Japanese speaker but like undrentide also mentioned, i can recall times when have identified the kanji of the word i was saying in order to clarify the meaning. Japanese without kanji would definitely not be a positive change.
I am not sure why Korea did away with kanji and I am only speculating here, but i would guess that Koreans did away with kanji more for political and nationalistic reasons rather than practical ones...
I agree with the semantic transparency of the word 湖沼学 when it is written with Kanji. However, it is also conceivable to come up with a term like みずべがく or ぬまちがく, combining native Japanese words and some (but not all) of Sino-Japanese words that are semantically transparent and actively used by many.
One of the drawbacks of kanji introduction to Japanese is that kanji use has spread too much in Japanese vocabulary, almost obliterating opportunities for words constructed with native Japanese morphemes to emerge.
Plus, it does not seem that the process of word coinage is purely driven by semantic transparency. Indeed, in many cases, the currency of a word does not depend on how clear the meaning of the word is. Say, 経済 and 環境 are hard to understand unless one knows the meaning of each word ahead of time.
Nothing is more clear on this when our attention is shifted to the ubiquitous spread of katakana words in recent years. Nobody can argue that these katakana words are easy to understand. Yet, the spread of such words is amazing but often saddens me.
I was watching a Japanese medical drama today and the word フェロー (fellow) caught my attention. The Japanese language has the word 実習生 for it, but somehow the English loan word replaced it. "ナースステーションNurse station" could have been 看護師室 or something else with native words. Everyone must be familiar with this trend. It almost looks like that the Japanese people simply gave up on coining new expressions themselves.
Anyway, my point is that the idea that the word's semantic transparency determines the use of language is not, in close examination, as verifiable as one would think.
As Chidoriashi mentioned, language policy is more related to other factors such as nationalistic pride (standardization of a language cannot be separated from this), learning issues, financial issues, and so on.
Koreans got rid of Kanji to unshackle themselves from the tainted past. They went great lengths to get rid of words originated from Japan and China. This coincided with their achieved independence after Japan's defeat to the war.
Japan and China once in the past envisaged getting rid of kanji altogether, for they perceived that their written systems somehow made them hard to catch up with the West.
Vietnam stopped using kanji because of the French occupation. They were forced to adopt an alphabetical writing system.
At this moment, Japan has no reason to change its writing system so I don't root for abolishing kanji, but abolishing kanji is not unachievable.
The society's mood has changed over the years too. The term 当用漢字表 (a tentative list of kanji characters to be taught in school) changed into 常用漢字表 (a list of ordinarily used kanji characters).