This is all just a guess but maybe the illagers are searching for the lost strongholds. Proof can be seen in that intent via the mock end portals made of wool seen in the woodland mansions. Perhaps these illagers wish to harness the powers of the end. Whatever the reason, they carved out the underground creating massive mineshafts whose sole purpose was to locate the end portal; hence why they left all the mineral ores exposed. Now I know that some of you may say that they've found strongholds intersecting with mineshafts. If this is the case, then the illagers have succeeded in finding the portal. However, the portal requires ender eyes which they lacked. As they search for more ender eyes they continue to conspire in their mansions. What do you guys think? Does this theory hold any weight?