TASM 2 has the same problem that many of MCU films from first phase has: too much focuses on setting up the next movies(TASM and sequels, Avengers) that they didn't bother to focus on quality of the actual movie itself. The movie has too much convoluted plot points that shove it into altogether, with handful of them are there to set up the cinematic universe.
The BTS fiasco wasn't helping. From what I remember, Andrew Garfield was very dissatisfied with how the movie was turned out and frustrated due to all the meddling from higher up. The Sony also tried to develop many spin-off movies that starring side characters, such as Black Cat and Silver Sable (Silver & Black), Sinister Six, Venom, Morbius, etc. With many of them didn't came to fruition at that time due to constant changing of the cast and developers.
One of the developing storyline of TASM 3 was beyond idiotic, with Peter was supposed to somehow resurrect death people, such Gwen and her dad, with some formula. and there was actual talk about making film that starring Aunt May as the spy when she was young.
The Hacking incident that leaked many of Sony's project was the final nail of the coffin as it revealed that Sony did contacted with Marvel to discuss about possibilities for add Spider-Man on MCU.