I'm not saying the movie didn't try, but it certainly didn't succeed in making me care. Also, given the tensions between Marvel/Disney and Sony, I'm not so sure Spider-Man will be the "centerpiece" of the MCU, if anything it looks increasingly like these Spider-Man movies are more interested in doing their own thing rather than serving a purpose for the MCU as a whole. With that, the MCU is kinda left with no real main character, certainly nothing like what we had with Iron Man and Captain America.
Yes, well it did gross over $1.1B in box office alone, close to $300M more than Guardians of the Galaxy 2 with less of a budget. Seems to have appealed to much of the wider audience, but you're welcome to your opinion.
Most of the solo MCU movies are independantly focused, with only a few loose threads placed in to connect them. That's generally the point of characters having their own movie. Considering the amount of involvement Happy and Nick Fury have, along with the consistent references to Iron Man all throughout the movie, it actually does more than most solo MCU movies to establish the wider narrative. It just happens to be more focused on character building, rather than setting up the next big event.