I dont know why but since i updated to the latest patch intermediate AI now doesnt build walls or if they build they dont finish them neither.
Example :
They build them but they dont finish it!! , in the gold version they didnt do that and they finish the wall with towers and keeps but now they dont try at all
i played like 6 matchs and in no ONE AI was building with stone . and in my last match the AI build that but didnt finish it , and i attacked them like 10 minutes later that wall was up