Please stop telling me that I'm allowed to improvise

My current "pet gripe" when reading modules is being told that I'm allowed to make changes or fill in details.

Let me be clear.  I know I'm allowed improvise, whether it's taking a pencil to the module when preparing for a session or just doing things differently at the table.  I'm pretty sure that everyone else in the hobby knows that they have the right to run a scenario however they want, too.  So why belabour the point in a module that's meant to save the reader's time?  It would actually be refreshing to read something like:

This is MY work.  I have tested it extensively and no improvement is possible.  By purchasing this product, you have acquired the right to run the module exactly as described within.  And if you dare make any alterations to this module when running it?

I will find you.

Instead designers seem to fall over themselves to give permission to alter details.  Worst of all is reading a disclaimer that certain details have been left out so that I have room to improvise.  It just staggers me that the conventional approach is to spend time telling the reader that there are details missing rather than spend that time filling in some details and let them go at it.

Writing this probably won't change things, but it needed to be said and I didn't want to single out any particular designer for making the claim.  If anyone has tried leaving off the "change what you like" disclaimer and gotten hate mail, I would love to hear about it!