Well, Hulk and Thor are both characters that Marvel owns. They have the luxury of using them to whatever extent they want.
Spider-Man, on the other hand, is on temporary loan from Sony to Marvel in a deal that could expire at any time and has to be used in a way that both parties deem to be mutually beneficial for as long as the arrangement lasts. The option of adding "more outside elements later" isn't a sensible approach in this situation.
Isn't the basic premise of the character what's most important?
The MCU is its own universe. It is not the 616 universe. It has its own continuity.
Adapting every aspect of Spider-Man verbatim from the comics into the MCU is not going to happen.