Computer speakers are almost always of the 2.1 type. That means a gap in the mids. You need 8-15 cm cones for the major part of the mid-frequency sound spectrum (speech, music), and that simply does not fit in most satellites. So there is no problem with car speakers (essentially the same as normal boxed speakers without the box), they are actually preferred above pc sets (also easier to built in nice).
Sure you need an amp, but there are very nice and affordable options for that. Most PC-sets have a simple D-amp-chip design built in, which is quite effective. You can also consider using the amp of a speaker set and attach it to decent large size drivers.
In the end it is also a matter of taste. Some like the punch of a 2.1 set, others prefer a more neutral reproduction you can get with car speakers.