"Can you make that hidden button always visible?"

What an easy request. Right? Just change the CSS to display:inline. An easy fix. In fact what could be easier?

Well maybe not so easy. What if that button does nothing until certain criteria are met (which is why it was hidden)? Often users do not understand that cosmetic changes have functional implications. Worse than that, changes are often made to design without asking about the functional implications.

For example, "What does it mean that this button is visible?","What now happens if someone clicks on a button which shouldn't be clicked under these cirsumstances?", "Should we throw an alert error?","How about an inline error?"

Why should you show a button which cannot by definition of the current spec even do anything at this point in time?

It is getting to the point where I just say "Yes".