I think your only problem is that you dont know how to write "Nintendo" :P

Yup, that's normal. You can still buy Mario Kart DS (if you're 'lucky') for launch price here.

So, in terms of years, Nintendo's been at it the longest. Hence, reharshing the most.

You can't possibly expect me to count both years and number of games. That's too hardcore, man.

Its because they estimated demand perfectly.
The only time games drop in price is when they have published a lot more than there is demand for, and so pass on discounts to retailers to cut the price. Even if they make little money, they still need to get rid of the stock in a more efficient manner than just throwing it away.

For some reason though, most publishers are pessimistic with handheld games compared to home consoles and the supply impacts the price of the games. On vita for example, AC liberation vita costs more than AC IV PS3 new, and black ops declassified (even pre-owned) costs more than COD ghosts PS3 new.... this is despite the handheld versions being OLDER. The handheld versions are certainly not better games as some people above have suggested as being a reason. Theres just not enough copies going around (compared to demand) for the price to come down.

So people expect me to believe that when Nintendo release a Mario Kart, on average, every 2.75 years, with all new gameplay, new maps, updated graphics, improved online etc. that's a rehash. But a Call of Duty every year, with new maps, and minor tweaks elsewhere isn't?

Or that Zelda, releasing on average every 2.6 years (taking into account only console entries); which again has a new story, new gameplay, new setting, new ideas, and new mechanics is a rehash, whereas Assassin's Creed which, release every year which feature a new story and, 50% of the time, a new setting, isn't?

Games in a series will, of course, be similar to past entries. That's why they're a series. This isn't rocket science guys.