In MTW you are wiped out easily if your general has 1-2 stars while enemy has 2- or more stars then you.
In RTW you will enjoy killing enemy generals who has 9 stars with your 1 star general.
That is the difference.
but people like seeing stars. I found them useless but no idea in M2TW or Kingdoms...
but in autobattles stars are very effective

like 230 HA Vs 600 phalanx
1 star 4 star
crushing defeat

same with human player in battle map
max 50 casualty (half friendly fire )
heroic victory all enemy wiped out...