Marvel Studio films are odd. What used to happen with CBM's is the first film comes out to decent/solid reception (as seen with even cap and thor), in instances such as Xmen and Spiderman and Blade, TDK etc. Then the sequel comes out and knocks things out of the park. Leading to conversations of greatest cbm of all time.
You saw it with most of those films. And it's no doubt way ASM2 and MOS2 will be great.
What marvel has opted to thus far is screw the pooch on their first sequels. The jury is out on Cap.
IM3 would have no doubt been in a bad place financially had it not be for the IM sequel that was Avengers putting the brand back in the red hot zone.