It's true. But if your computer is all you really use, then why not? I'll never need a good soundsystem for my television because I only use it for playing console games. My computer however is how I watch shows, movies, listen to music. Makes more sense for me to have good computer speakers over any others. Granted I'd probably invest a lot more into my car's audio, but that's always more expensive.
Oh I love the engine too. But I'd rather have everyone else around me hear how good it is, whoever's in the car with me will already know. But good, crisp audio that'll still be crisp while loud as hell? Just so good. I'm a big music guy (play bass, played tuba, baritone, trombone, and 4th bass drum in HS band) so good sound is important.
I personally always prefer Bose stuff, the quality really is some of the best. But that would be dropping anywhere from 1 to 3 thousand, maybe even more; too brokes for all that, that's a third of a decent used car.
Just to let you know, there are plenty of people in the audio world who would probably disagree with you on that assessment of Bose. I personally think they sound arlgiht, but there's a large group of people who simply think the company is a marketing tool.