What is the point of transparency?

I wish programmers would stop using transparency. It is commonly used these days and Windows default desktop theme has transparent window borders, Lion on the Apple Mac has user interface elements that are semi transparent, and even Facebook uses transparency effects when you view a photo.

Semi transparent objects do not improve a user interface or make things easier to use. They make it harder. To see the effect of transparency, get a marker pen and write something on the window, then write something on a white piece of paper and compare the two. Which is easier to read? It's really hard to read what's on the window because you see right through it to the background. We don't use complete transparency in programs and user interfaces on computers and devices, and usually semi-transparent items are used. This isn't quite as bad, but it still makes things awkward to see.

It's a no-brainer, but programmers don't seem to understand this. It is a clever graphical effect that looks impressive when you first see it, but it just makes things harder to use. Graphical effects should only be used where they make things simpler and easier, and they are not to simply show off a programmer's skills.

Whenever possible I turn off transparency effects, but there often isn't the option to do this and we have to suffer the problem of trying to read text or view something when the background is showing through and confusing us.