As a fan of film music since 1977/1978 (specifically science-fiction scores -- my aunt had the Star War soundtrack on 8-track as my first exposure), a few semi-coherent thoughts...
1. Star Wars is 39 years old (2 generations old), and James Bond is 54 years old (2.7 generations old). Even the first Harry Potter movie is 15 years old. They are part of the public/pop-culture consciousness. In that respect, the Marvel franchise is still relatively young and covers a WIDE variety of different films; I'm not commenting on their musicality, and you could say there's little carry-over of themes within each sub-franchise (Iron Man movies, Captain America movies, etc.).
2. The above (non-Marvel) movies were written with the Wagnerian leitmotif in mind -- recurring themes linked to people, relationships, and actions.
3. For many movies today, the music is merely sonic wallpaper.
4. The video rebuttal is quite right; at a movie music website I browse, many forum contributors there detest and blame Hans Zimmer and his various acolytes & proteges for the "sad" state of what passes for "film music" these days.
5. Would thematic music be better for the current crop of movies? Probably, but this is where we are at in the current "evolution" of film music.
6. The concern over the lack of "hummable" themes in the popular Marvel movie franchise is a bit overwrought, IMHO. MUST it have better music, for what it is? Silly moving pictures about superheroes?
As one forum contributor mentioned, the music serves the movie; the movie does not serve the music...
7. Even if they are not blatantly repeated, there are musical themes in the Marvel movies -- if you know where to look for them. Though there was no specific theme or main title of which to speak, I bought the score for "Guardians of the Galaxy" because it has a nice number of one-off themes.
I also like the Transformers scores; Steve Jablonksy (a Zimmer protege) has a nice heroic Autobot theme, among others.