Well, this forum has died down significantly since a month a ago so how about some friendly crossfire on hidden buttons?
To start, I'm an Anti-fan of hidden buttons unless in extremely reasonable circumstances, and even then will not use a Secret Button. If it's part of a puzzle or progression [of any type] the notion to apply something "hidden" never arises. I always try to present dungeon progression as logical path, though with obfuscation, markers, story presentation, or visual representation.
With that said, I don't mind a module to have secret buttons either as long as it's a reoccurring mechanic that represents a facet of progression. So if I find one hidden button I expect to find another one some time down the adventuring path, as well. So basically, if I were to use secret buttons "I will want this to be a mechanic applicable to certain actions and events to keep concurrency."
While I very much enjoyed the campaign there was instance this occurred I thought the use of secret button was out of place. I don't remember the map name but the puzzle dealt with two movable push_blocks and the only way to solve it was to open a secret door and get behind it. Well, I could plainly see I needed to get on the other side of the wall but being I wasn't aware of "forest" type of secret buttons I was looking for much more complex ways of getting behind the wall instead of strafing around looking at every pixel of every texture.
My follow-up: all modules that have secret buttons "probably" should tell the user there will be secret buttons without getting into too many details. Modules that do not use secret buttons "always" should state up front there are no secret buttons (or at least in the case the secret buttons are never part of progression).
So, what do you onThink?