I dont think ever new game is better then the older version of the same style.
Dune2 was remade by westwood a couple of times and was never as good as the original even though it had better graphics. I loved Z, but Z2 sucked ass even though it had 3d etc. Warcraft 2 was killer, warcraft 3 made me yawn, the units were too powerfull and the defensive buildings were easy to take down.
Just because the graphics get nicer and the game gets more complex doesnt mean its more fun.
Look at the evolution of FPS type games, went from sort of 3d using sprites to actual 3d which allowed for better physics models. Tossing the grenade down a spiral 3d stairway and watching it bounce till it detonated on the head of an enemy was gratifying.. something your couldnt do in a 2d world. FPS started the home LAN, doom2 parties were so much fun. You could actuall coop in doom2 that was fun. Games like tribes and Unreal tournament added the capture the flag mode where teamplay meant the difference between winning and losing where all the old games were run in circles and shoot anything that moves. games like theif added 3d sounds where things could be heard behind you while you played added to gameplay. One of these days we will all have a headphone and mic so that we can all talk in real time that would add to the game immensly. There is always innovation, just takes time.