Part of the problem is that when SHIELD and Carter were pitched, Disney/Marvel thought they could woo everyone that ponied up for a Marvel movie to watch a weekly Marvel-themed TV show. What that strategy failed to account for is that a lot of the Marvel movie audience is there for the casual thrills. They're not dedicated enough to watch the more modestly budgeted shows and the ratings have shown that. Even the attempts to tie the show into whatever movie was about to come out, like Sif's story in SHIELD, didn't draw any appreciable rise in viewers.
On top of that, Marvel's strategy of using SHIELD to push the Inhumans stuff has kind of backfired. Marvel Studios had that big management shake-up that screwed the original plan over. Meanwhile, the X-Men, unlike Fantastic Four, continues to be a popular movie franchise and brand so even fans have resisted the Inhumans concept.
AFAIK the pitch for Marvels Most Wanted was done back when Disney thought their Marvel-themed TV superhero stuff would really take off. It hasn't. At least not enough to justify the expense needed. I'm not sure if they figured out they were boned too late in the SHIELD production process to pivot, or if they really thought they could make a go of it, but it sucks for Adrianne Palicki.