I think people fail to realize that when Gen. 1 was first introduced, there was NOTHING previous to compare it to. We shouldn't be comparing the new generations to the older ones. Also long as we don't get a Pink mouse Pokemon called "Pinkachu", then they aren't repeating themselves.
Think about this: The 5th Generation had no connection to any of the previous 493 Pokemon, no pre-evolved forms or further evolved forms. They introduced a totally new set of stand-alone Pokemon. (Not to mention, we got 156 new Pokemon, 5 more than the original games.) Also, look at White Kyurem and Black Kyurem. This is a new concept in having a Pokemon change formes to take on features of another. Black 2 and White 2 were a complete surprise to everyone, so Game Freak has proven that they aren't as predictable as some of us thought.
Everytime new Pokemon are introduced, the designs are attacked. Yet, if I remember right, Black and White are the most successful games in Pokemon history. People seem to just like attacking new Pokemon and comparing them to Digimon and Yu-gi-oh. However, after actually playing the games, they come to like them.
The Pokemon themselves are far more interesting than the first ones. In Gen. 1, all they were were creatures with powers that battle. These days, Pokemon actually represent deeper concepts and can control time, space, and we even have a "god Pokemon". Sure, they could try not to repeat a Fire/Fighting started for Gen. 6, but that's just a minor thing. Gen. 1 had THE most simple Pokemon design ever: Voltorb. Also, I personally think that Exeggutor is the strangest Pokemon ever. (Think about it: 6 eggs evolve into a pineapple?!) Truth is, even the very first Pokemon are sort of strange, so simply saying "the new Pokemon look stupid" makes no sense.
In the end, whether you like certain Pokemon or not is just taste. However, Game Freak is clearly still creative. Also, it's totally justified for more new Pokemon to come in the future. You may think that 649 Pokemon is way to much, but there are far more creatures on this Earth than just 649, and many just waiting to be discovered. (Just saw this morning that a new frog species was discovered in New York.) Don't be so quick to judge Game Freak.