Total logic elements increasing

If my guess applies then there is nothing wrong. You don't need to worry, just connect your inputs as they should be.

Let me rephrase what might happened; an input port at top of project is assigned a pin by compiler. To the compiler a input port will get its drive from outside and so is non-static and must be respected...

On the other hand an internally declared signal instead of port may be static unless driven from outside indirectly. By static I mean undriven internal node which may default to zero. In this case all the logic related to the case of '1' will be removed because the compiler sees it is never going to occur.