I think one of the signature accomplishments of RTW is that it's credibly possible to argue that both units and their counters are over-powered in the same breath.

In reality, this issue may be more that the AI is underpowered.

Give me 4 units of phalanx and I can probably beat the AI's 4 units of cav with minimal losses. Give me the same 4 units of cav and the AI the phalanx and I can probably reverse the outcome.