Are you asking if anyone values the espionage features in Civ IV, and thinks it worthwhile to keep in mods / new releases of the game?
If so, my answer is HELL YES!
My feeling is that Espionage may be undervalued by the community because it isn't well understood, and like many aspects of the game it isn't fully explained by the documentation or Civilopedia entries.
For example, I think espionage plays an enormous role in diplomatic tensions, especially early game. How? If I've discovered one other Civ, but I notice that turn after turn he's not able to keep up with me EP point-wise, I can conclude a few things: 1) He's met somebody else, and 2) Rather than drop his guard completely toward the other Civ, he's having to balance his EPs between us both, which is leaving him vulnerable to us both. I think these sorts of balancing acts go a long way toward explaining why some Civs the minute you meet them are "Annoyed" with you for no reason.
And while I can't prove it yet, I'm willing to bet that EP spending / rival targeting has an enormous influence on how and where barbarians spawn. From what I've noticed, barbarian spawn is about as random as the so-called random events. There's method to it.