Scutage was a good thing. First of all, if you were a French or Anglo-Norman noble, you were generally only required to serve for 40 days anyway, which really limits the King to a short ineffectual campaign. Second, a great many of your "troops" were worthless in battle, because only the cavalry was really trained, and maybe the archers if you were English. Last but not least, while say the Earl of Leicestershire would not mind to fight somewhere in England, he wouldnt want to leave his lands and cross the Channel unless he was going to profit from it. So only the English nobles who actually owned land in Normandy were really keen to serve there, and even they wouldnt care to venture further afield to say Gascony or the Toulousaine.
But with scutage, the King can rectify these problems. He can use your money to hire much better "professional" troops, like Welsh archers or maybe some Brabantine pikemen; they will follow him anywhere he wants as long as they get paid; and they wont care how long theyve been in the field because they 1) want the job, and 2) dont have a huge fief to get back to.
So I hope I can raise scutage in CK, because instead of a chaotic feudal host, I'll have an invincible army composed of Brabantine pikemen, Franconian knights, and Flemish crossbows...and this time the Emperor's gonna sweep the field at Legnano...