Having played the first Resident Evil title upon released, I was very impressed with the quality of gameplay and developer interaction. However, as Capcom has grown in size and popularity, their reason for developing games has shifted greatly, to having the sole purpose of making money. Therefore, I have seen the quality of their series drop greatly, and have stopped playing the games.
Initially, Resident Evil was a groundbreaking game, the first of its kind and it thrilled audiences. Despite changes in gameplay, the games themselves are very similar and with each sunbsequent game, the franchise becomes less appealing. As the zombie horror genre became more popular, a surge of zombie games meant that Resident Evil got lost in the jumble and has been unable to differentiate itself since. While the first game is a classic and remains one of the best games all round, recent releases have been subpar and poorly received, signalling that the game's popularity is fading.
Every player has their own preferred game, and players always look for a new version of the game once they have mastered the current version. Boredom is not a good thing with a game, it might cause the players to look at other games and never come back to Resident Evil. And everyone needs their daily dose of zombies!
There are not too many Resident Evil games. I can see why some people are saying they are, they seem to have release an unprecendented amount in a short space of time, usually sub-plots of other games that they had previously release, but I love the games, and I think the more the merrier!