3.23 The requirement of the possibility of simple signs is the requirement of the definiteness of sense.
So if sense is to be definite and not vague then there must be, or it must be possible for there to be, such things as simple signs. See my comment on 3.2 for why we might not insist that sense be definite. But if what can be said can be said clearly, mustn’t sense be definite? I don’t think so. A vague sentence can be quite clear, as the later Wittgenstein certainly realized. If I say “Stand near the door” this is vague but, possibly, quite clear.
This connects with Frege. See Basic Laws of Arithmetic 1903, v. 2, §56 and §62.
See also Mounce, on what the point of a logical system is for Wittgenstein (this comment might be better elsewhere). (p. 48) “it is not the purpose of a logical system to provide a language more perfect logically than the ordinary. Such a project, on his view, is entirely incoherent. One thing cannot be more logical than another. A thing is either logical or it is not; it is either meaningful or it is meaningless. Thus, the purpose of a logical system is not to provide the logic that ordinary language lacks; rather it is to display the logic of ordinary language more perspicuously than ordinary language does itself. But then it follows that the cardinal sin in a logical system will be lack of perspicuity, vagueness, ambiguity.”