Reviews of Games?

Why are almost all reviewers biast, without seeming like it. for example in a Resistance fall of man review they gave it a low score for being like halo. HOLD UP wouldnt being LIKE halo good? If halo is soooo great then people should play games like it rght? also with mario (I love mario games and am NOT saying they suck) but reviewers are always like "this sequel is like the original 3/10" when mario games are almost EXACTLY the same. you jump. and then get a mega mushrom. then jump. it's the same! i just have noticed tha s little and wanted to share my incites. Some may be asking "is this a question?" well im about to tell you! okay so tell me your opinion, do you think im right or wrong? Give some evedince Please!