Short, but accurate story (imho ofc)
-Strerched too long past the tolerable length.
-The reveal that Peter was the clone .
These two are the main reasons why it didn't work in the end. Marvel almost had its cake and was on the verge of eating it. Instead the slipped and the cake was splattered all over their faces. At that point they had to kill Ben.
Nowadays, there's no need to kill Ben ir ruin him like they're doing.