The problem with high information-density languages (and the reason human languages don't exhibit a similar economy of meaning) is that, even disregarding their complexity, they quickly become impractical for real-world use.
Think about English; it has a lot of redundancy, and even if you leave quite a lot of gramatical information out of a sentence, a reasonably competent speaker can deduce what you're talking about. n f th bst knwn xmpls s drppng ll th vwls frm sntnc. You could also drop all the articles, or prepositions. The advantage of this is that on what information theorists refer to as a "noisy channel" (a crowded room, a bad telephone connection, etc.) the redundancy means that even when you don't hear (or read) 100% of what the other person is saying or writing, you can infer what is missing; this is why, despite wild variances in phonetics and grammar, all human languages have about the same informational density. Unfortunately, it also makes constructed languages like Ithkuil and Speedtalk somewhat impractical (although they are still fun as philosophical and artistic exercises!).
