I think it is best when players are given the opportunity for either stealthy or upfront approaches. Try playing Far Cry on "Realistic" difficulty. You can creep past enemies moving from bush to bush but if that gets tedious then you can stand up and own the shit out of some bad guys if you are godly enough.
The real fun from this hybrid type of gameplay comes not just from shooting people in the face before they can shoot you, but from outwitting the AI which are pretty intelligent.
JC Denton: "I know your UNATCO killphrase: Laputan Machine."
Gunther Hermann: "I - am - not - a - machi --"
JC Denton: "Sticks and stones..."