Turning on debug mode is a matter of pressing one hotkey... who can't resist now, won't be able to resist anyway.
I don't think it's true at all. That's like saying that seeing all map is just a shortcut away, so who wouldn't do it, right? And I think the temptation is much greater in battle.
Also remember that most players don't even know bug mode exists.
In my opinion, it's a useful functionality and only very remotely a cheat... modders even provide the tech trees with their mods (e.g. FMP or Hardmode). Many games come with techtreeviewer built in (e.g. Civilization).
Yes, but Civ is a different type of game; it doesn't have the adventuring component that
Piratez has. Civ wasn't designed to block the info from the player, while X-com kinda was, even if at this year we all know the tree by heart.
I think it should at least be enabled by an option and adequately described.
EDIT: If the viewer was limited to only show the next level of researches (directly descending from a tech you have), I'd be perfectly okay with it.