I need to preface this by stating that I am a huge fan of what EPCOT Center had to offer back in the 80s and early 90s; the attractions and experiences were novel and incredibly well designed. What we need to understand, however, is that these experiences are never returning. Ever.
The fact is, Disney is a multi-billion dollar corporation, and their primary interest is maximizing profit; that's about it. Everything else, like customer satisfaction, design, and creativity, comes second. The harsh reality is, when boiled down, creativity from WDI is simply a tool to maximize profit.
When Walt Disney founded Disneyland, I'm sure that his intentions to create a family-friendly destination that could thoroughly be enjoyed were genuine. Let's not forget, however, that Walt Disney was indeed a businessman and a good one at that. Walt's corporate mission can really be condensed down to this: give the masses what they want. If the masses with wallets demand it, build it. Guests wanted thrills, so what did Walt do? He built the Matterhorn.
Indeed, many people would pay good money to see EPCOT Center return to its former state. However, this number is simply not large enough to sustain a massive theme park. Disney is going to be putting IP's in Epcot, and that's final. Why? It's because they masses recognize these properties in the mainstream. Frozen replaced Maelstrom because Frozen made a boatload of cash and sells tons of toys; that's about all the justification Disney needs as a corporation to make such a decision.
The argument that Disney needs to remain true to the mission statement of EPCOT Center is admirable but quite naive. Again, the reality is, no company looking to maximize profit will forgo opportunities to do so. Moreover, such a company would never do things to hinder profit maximization, and bringing back fairly unmarketable and unrecognizable experiences would do just that.