There's been a lot of complaints about well, basically anything Disney has done since Indiana Jones opened. Toontown is not that well loved. Winnie the Pooh sees nothing but complaints. Monster's Inc. is somehow not up to par. BLAB and Midway Mania are still somehow not good enough. FNSV is seemingly despised if forums like this are any indication. The complaints are very vague, though. Some about matching land theme have merit, but these complaints ultimately say nothing about the ride experience itself in isolation. Most ride-specific complaints are very vague: "not up to par, not good stortytelling, etc." At some point somebody actually said, in reference to the "problem" with Winnie the Pooh: "You see it or you don't." implying that the problem is actually not even able to be put into words!
So what the heck is going on? I think I know, and it all boils down to Fantasyland.
1) People don't like the concept of Fantasyland leaving the borders of Fantasyland. They don't like Fantasyland style rides outside Fantasyland.
2) People don't realize how simple/dated most of the Fantasyland dark rides are. Or they do but forgive them for nostalgic reasons.
So let's at these two issues:
Problem #1: Fantasyland outside Fantasyland
Disney has a land full of old characters that no longer resonate with children. Sure the rides work and the characters are timeless, but Disneyland was never meant to be a snapshot of 1955 forever. Disney has countless beloved animated characters that have come out since 1955 and the Disney company would be foolish to completely ignore them. People are always asking why X character and Y movie are not in the park.
Retrofitting the Fantasyland rides with new characters/themes would be a PR nightmare and eliminate a great deal of the nostalgia on which those rides rest. So Disney's only real option is to allow animated characters and attractions based on them to exist outside Fantasyland, allowing attractions incorporating post-1955 characters into the park. This decision seems to date to the 80's, arguably with Star Tours, Toontown and Roger Rabbit represent a full land of characters outside Fantasyland. The first retrofitted character additions start in the 90's with Alladin's Oasis, Tarzan's Treehouse. Not coincidentally, the 90's also represent the time at which Disney had any animated properties worth a damn since Walt was alive.
People have complained about every single Fantasyland-style attraction that has been built outside of Fantasyland's walls. People are complaining about too many movie based rides and characters taking over the park.
What's going on here?
Basically, Disney has a mountain of characters that they were trying to cram into a single land. Allowing this wall to be broken is a change in fundamental approach for Disney, but it's one that is hard to deny from a practical standpoint. Not allowing character based rides outside of Fantasyland is just too limiting and turns Disney into a museum dedicated to 1955.
Is there hope?
I think the allowing of Fantasyland attractions throughout the park is here to stay. If this fundamentally bothers you, then Disney theme parks are going to fundamentally bother you from now on.
I think if Disney were to install an E-ticket that was not based on a movie property (in the vein of POTC or HM), people may be more accepting of the Fantasyland style rides outside of Fantasyland. Right now there's no arguing things are very imbalanced, even if Fantasyland style rides outside Fantasyland is ultimately accepted.
Problem #2: New Dark Rides in a post-POTC World
People love Fantasyland and Fantasy-land style dark rides. Rides in this tradition have not been built since the 1950's, excepting some Fantasyland additions in the 1980's with the refurb. Fantasyland is out of room, so more Fantasyland refurbing is not an option (see problem #1 above).
Disney begins building rides in this tradition again. Although updating the tech of them, they are built in the same tradition and fashion as the original dark rides of 1955. These rides are Roger Rabbit, Winnie the Pooh, and Monster's Inc. (we're going to ignore Superstar Limo as a drunken mistake). Also arguably including BLAB and TSMM.
But these rides aren't good enough, for reasons unclear. Roger Rabbit seems to go over okay, but Winnie the Pooh is said to be "cheap", despite having much more flourish and tech than almost any other Fantasyland ride. It's said to lack story, yet a hatched and abridged version of Snow White that completely lacks an ending is beloved. Monster's inc is said to be static and yet Mr. Toad, a ride made entirely of painted wood panels, is beloved. FNSV, which attempts to break out of the original Dark Ride tech boundaries, gets lambasted for NOT being a dark ride and just being "video screens".
What's going on here?
Primarily, Fantasyland CAN NEVER HAPPEN AGAIN. Quaint, relatively cheap dark rides are no longer enough for guests. It is nostalgia that primarily keeps the old, dated, cheap Fantasyland rides "acceptable". Fantasyland was build pre-POTC and POTC, as the most elaborate and themed dark ride of all time, changed expectations for all dark rides forever. Haunted Mansion met this expectation. Indiana Jones somewhat meets this expectation. But anything built that could be categorized as a dark ride has NOT been a hit if it has not been built with the same elaborate quality as POTC.
Is there Hope?
The Little Mermaid might pull it off. If it's elaborate enough, people may accept it. But if it strives to be Fantasyland rather than POTC, then it will likely be met with mixed reactions at best, just like every other dark ride that came out post 1969 that doesn't have Indiana Jones in it.
Disney's true attempt to solve this problem has been to move away from dark rides to other technologies. This is BLAB, TLMM, and FNSV. These incorporate interaction and video technology to immerse the rider instead of expensive sets and AAs. Is it working? It's tough to tell. These rides all seem to be popular and yet hated for one reason or another. It could be the usual resistance against change. But the reality that not every ride can be POTC may just forever be a bitter pill for the fans to swallow.