general scanline question

this is kind of a weird question, but any comments/responses are welcome:

How come lots of business websites use scanlines in their graphics? I don't know if it's just me, but it seems to be a popular theme among a lot of business sites I've been looking through recently, even though its might pass as an unnoticed detail. Some examples that come to mind:

www.ibm.com
www.ultimatte.com
www.dell.com

its trendy and IBM's logo always looked that way.

yeah, trendy in a not-so-in-your-face-matter i think.
It´s a good and neutral way to decorate the elements. Ppl just like to play it safe when it comes to corporate-websites, which is understandable, I guess.