Spies are already quite expensive and it would be hard to amass even 50 of them, making the +100 spy bonus kinda pointless unless you have a nation that has enough excess wealth to buy that many spies. Many small nations will gain no benefit from having an intel agency as they simply can't buy 50 spies for a long while, unlike other improvements which benefit your nation regardless of how large it is.
I think it would be better if intel agencies made spy operations cheaper or increase the likelyhood of success instead of (or as well as) increasing the number of spies you can have, this way smaller nations can make better use of the spies they do have.
This post has been edited by Anatidae: 29 September 2007 - 01:38 PM