Lots of reasons really.
Back when the ride originally opened it was twice the length it is today and was actually considered good. And since then Disney have changed it a few times, and has gotten worse each time and the ride length got cut as stated. And now we have that awful ride we have today. The classic 'Dreamfinder' character was cut and Figment became annoying lol The ride is just bad all round.
Not only that but above Imagination was a big interactive 'play ground' type thing which was closed off and abandoned which people have been bitter about. A similar thing can be found at the end of the ride but on a much smaller scale. There was also a Figment M&G in a room to the side which has also been left abandoned.
Then on top of that Captain EO and Honey I shrunk the audience were left to play well past their welcome which was just cheap and lazy. And now they have both been replaced with a Disney-Pixar short film festival which again was a cheap move especailly so since all the movies playing have already been seen in theaters, on DVD and online. So again, nothing new there.
The whole paviliion is just a complete disaster and a husk of it's former self and needs a huge overhaul.