getAppProperty(String key) is instance method in MIDlet class. Since all midlet in midlet suite share same manifest/jad file, so why cant it be a static method?
If the phone runs several MIDlet suites inside the same JVM process, they all share the same MIDlet Class object.
If you then make the method static, it won't know which JAD file to retrieve information from.
Neither the CLDC nor the MIDP specifications prevent phone manufacturers from running several MIDlet suites inside the same JVM process. It is in fact more efficient to do so in a resource-constrained environment.