[WraithLord]

I've played the warlords series, age of xxx and other TBS/RTS that implemented this system.
Some implemented it very badly some better.
For example, the age of XXX system is horrible. both shallow and extreme. really turned me off and is the main reason I stoped playing them.
OTOH the warlords implementation is more subtle and added depth, diversty and increased the fun factor in the game.

buttom line I agree with saber, this system can add a lot to the game if it's introduced subtly.
If the devs don't have the resources/inclination to do so carefully then I prefer they leave it be.