It's simply that the movie lines get better teams to work on them and more invested into them.
You can't say anything other than that.
The MU line cuts A LOT of corners. Inappropriate reuse of molds and a lack of sculpting and accessories really hurt the line.
For example, when MU reuses a figure, they don't even bother to add sculpted belts, etc.
Several examples of movie/MU figures kill your "spandex theory"
Captain America - movie version is easily better than any of the MU versions, even though they wear the same costume.
Winter Soldier - same exact outfit, but the movie version destroys the MU figure.
Classic Ironman - same armor, but the IM2 figure is 10X better than the girly MU figure.
However, the Wolverine movie figures didn't really hold up their end of the bargain. They were seemingly rushed into production. Most of them have bad face sculpts and they cut corners on guys like Gambit. I prefer the MU Colossus (especially the upcoming 6-pack figure) to the XMOW Colossus. And most of the MU Wolverines are better than the XMOW versions.
Anyhow.. we see with several of the upcoming figures, how great the MU line can be if they just put in the effort and stop half-assing it. The new Cyclops is the best Marvel figure Hasbro has ever done in any scale.
Completely agree, the only thing that was done right for XMOW was the size of wolverine scale wise, and the unmasked wolverine, not to mention comic deadpool and comic sabretooth. And they fixed x-team wolverine(htey copoied my custom). Bit i'm guessing the comic version of thor from the movie is gonna rock!!!!!