In the example, there can certainly exist a logical relation between the two propositions (inquisitive students - make - better students), however, since there is not enough information, a logical relation between them cannot be properly constructed. If the comparison presented some sort of argument then it would be complete. For instance: "Inquisitive children, <em>since they are more curious and open to learning</em>, make better students". Without the argument, the idea seems more like an unsustained opinion, based on prejudice, than anything else.
A comparison is a consideration or estimate of the similarities or differences between two or more elements. In the sentence "better" is a comparative adverb, however, the sentence does not compare one element to another, which it's an indication that the other element is missing, the comparison in incomplete. Here is one example where the comparison is complete "Inquisitive children make better students than lazy students because the first group tends to be more eager to ask questions and solve problems."
