That's because the original T1 was a classic though, followed up with another classic sequel in T2. These are indisputable movie classics, like Alien and Aliens. Spiderman has never had that. Sure there are fans of Raimi's trilogy, but I doubt many would call them classic. There isn't a perfect genre defining Spiderman movie, there is no point of reference to hold up every new release to. Just lots of movies with good elements to them, all different all failing in some way. Therefore it leaves hope that there will be someday in the future.
Up until recently I had thought Spiderman 2 was considered a classic of the genre. Now apparently a bunch of people think it's crap.