Why can't I finish video games?

Something weird has happened as I've gotten a bit older, I just can't bring myself to finish a video game anymore. I have all these awesome games for my Xbox (Ninja Gaiden, Halo 2, Jade Empire, just to name a few) and I'm RIGHT there at the end basically. I'm normally within 2-3 levels of completing a game and then I just sorta stop and lose interest after going around and blasting or slicing to death thousands of computer generated enemies with glee.

The only games that still seem to catch my interset are games that don't have a definate end. I still keep on coming back to games like SSX 3 (thats for my GameCube), Burnout3, Dead or Alive 3 (talk about old school, thats first generation Xbox right there), and Soul Calibur 2.

For example, last night I threw in Halo 2 to see if I could get back into the game. After about 5 minutes of blasting Flood and Covenant bad guys I got bored and turned off the game and switched it to Dead or Alive 3. I proceeded to play this for about half an hour in Survival mode just to see if my skills were still decent at ass whoopin. I must admit, my skills are still there for certain characters like Ayane and Kasumi but I would have to practice a lot in order to beat my all time high of 47 knock outs (I average about 15 these days depending on the character I'm using).

I'm even wondering whether or not its worth my getting an Xbox 360 (for those of you under a rock, thats the new Xbox game console slated to come out this fall) when it comes out or if I should just wait and try and beat some of my other games first. Oh well, I had such a good time with DOA3 last night, I think I'll play it a little more tonight just to whoop some computer ass. :)