Because people can still play their old 3DS games, so nothing was really taken from them that they don't already have? The new 3DS is an updated, more powerful version of their device that happens to take advantage of that new power by releasing software exclusive to it. If you have a GeForce 256 card, do you bitch that it does not play Crysis, and that you need at least a GeForce 6800 for it? No. You don't. You shut up and go back to playing Quake III instead.
Jesus Christ, will you stop it with the "big fuck you" bull? This is a device that is more powerful than its predecessor; if it is able to play a game that can't be played on an OG 3DS, why wouldn't someone take advantage of it? Did you make a big fuss when the GBC got Pokemon Crystal as an exclusive?
When this gets released, will your existing 3DS cease to play all current 3DS games anymore? No. Like all new techs, it will have features that an older version will not. This is not done to spite you or anyone; it is just natural for them to take advantage of more powerful hardware. This isn't some big conspiracy to rob you of Xenoblade Chronicles, or any future exclusive New 3DS titles. It is the nature of the beast. If you're raging that your less powerful device is not getting the same stuff that the newer tech has, then you might as well give up technology, bud. Because it fucking marches on.
Did you know that when the DSi was released, the DS Lite was just a little under 3 years old? Did you rage that time too?