Multimedia sound cards don't have a great reputation in the music scene, although many musicians use them. It is absolutely true that the demands of multimedia and those of musical creation are very different in almost every respect. You might therefore be understandably surprised at the persistence of a large number of buyers who keep using multimedia cards as a substitute for musical instruments.
The primary reason is certainly the price. A sound card designed for musicians continues to be much more expensive than multimedia cards. But you shouldn't ignore the fact that these cards are in widespread use. Musicians - especially amateur ones - aren't always playing music, and the ability to use the equipment for fun is a compelling argument. Not to mention the fact that, installing two types of cards (multimedia and "music") multiplies the complexity. Multimedia card manufacturers have also strongly encouraged musicians to use their products by making claims - not always very objectively - about their composition features. Yet, to produce sophisticated music, you need products specifically suited for the purpose.
This is where the E-MU cards come in. On the down side, there is no way they can be used for game playing or DVD playing, to name just two popular pastimes. But that's because these cards are solely for musicians and sound creation enthusiasts who demand professional quality sound production.