Why those mirror displays on laptop computers?

Glossy displays generally give a brighter, contrastier picture, but as you've noticed, they are highly reflective under any kind of light. They are okay in doors and even better in low light conditions. However, in anything more than moderate office light, they can be a real pain.

As for matte screens, they are getting a bit harder to find. Apple offers them as an option on the MacBook Pro, which means that they can be a little bit hard to find unless you are ordering new, and they are standard on Lenovo's ThinkPads. IMHO these two marques are the only really excellent laptops out there. Though I suppose that if one looked around, you would probably find them at least as an option on some business class machines. I might add that Panasonic's ToughBooks have an excellent matte screen which is very bright, but they are exceedingly costly machines, neither particularly large nor particularly powerful, and rather heavy for their size, though they are incredibly tough.

There are a number of vendors which sell anti-glare film overlays for various machines, if you wish to go that route with your present machine, but be aware that you will lose some brightness and contrast, and your screen must be absolutely clean before you apply them.

Contrastier?

Even though it doesn't seem like a real word (to me, anyway), the idea was communicated quite nicely!

the panasonic toughbook has that type of display

The issue is that the modern screen resolution is approaching the feature size of the matte coating on the screens, so the screen appearance starts to look blurry and due to internal reflections in the matte layer, the light transmissivity goes way down too, making the screen appear darker which ironically makes such screens harder to see in bright daylight anyway.

LCD's have a limited contrast capability anyway, if you jack up the brightness of the backlight, blacks start looking gray, and since internal reflections can reduce the light transmissivity of the glass by HUGE amounts (more than 50% in some cases) LCD manufactrurers are doing everything they can to decrease internal reflections such as putting coatings on the glass that reduce internal reflections and eliminating matte finishes in order to improve the contrast ratio.

Damned if you do... Damned if you don't...

Um, LCD screens are made of plastic, not glass. I might also add that modern screen resolutions are not all that much greater than ten and fifteen years ago. My 486DX4 had a 1024x768 monitor back in 1995. My Lenovo T61 has a resolution of 1440x900, and the newest 16:9 laptop displays are little different.

Other than that, a pretty good answer.