I have to agree with KevinPage. Let me use myself as an example. Growing up, I had my own pre-concieved notions of certain attractions that are still there.
Example 1: "Carousel of Progress." Now, as a kid, depending on your interests and also hearing your mom saying that it was "Okay, but kinda boring. You probably wouldn't like it." Well, you'd get the notion stuck in your head that it's not something you want to go on, right? That's what happened to me. But back in June, I was at MK on my own. No one else was with me. So what did I do? I decided I would try things I hadn't and actually give them a chance. The first thing I tried was CoP. I went in with an open mind and came out singing "Great Big Beautiful Tomorrow." I was totally surprised by how it defied my expectations and now I enjoy going on it. I went a second time on that trip and then brought my family on it in August.
Example 2: "The Land." Well, I went to the land about 15 years ago. Didn't spend much time there. Didn't remember much about it, so I figured it probably wasn't that great. I didn't ride "Living With the Land" because I thought it would be dull and again, my parents had little interest in it. Well, I didn't go back as a result. Again in June, doing things I hadn't done, I went to "The Land" after being convinced by a separate thread here to give it another shot. I rode "Living With the Land" and took some pretty good pictures. I had a Strawberry Shortcake at the Sunshine Season Food Fair and I also went and saw the "Circle of Life" movie. As far as the movie went, I could take it or leave it, but I went on "Living With the Land" again in August when I brought my family back and we had breakfast at Sunshine Season Food Fair. Now I'm sorry I didn't go back sooner because with the addition of "Soarin'" it's going to be radically altered.
To a lesser extent, we have Example 3: Test Track and Mission:Space. My favorite attractions other than JII(the original) at Epcot had been Horizons and World of Motion. Both are now gone, but they were replaced by other attractions. Both other attractions looked to have the potential to be good so I went and had a blast on both. I know not everyone likes them, but I do so even though I don't like that my old favorites are gone, at least IMO they didn't replace them with utter crap.
And finally, I don't know what's going into the 20k lagoon. All I know is that another old favorite of mine is no longer there. What does this mean for me? It means that there will someday be another attraction there(we hope) and that whatever it is will be something worth at least trying. I will no longer look at something that is built at one of the parks and just dismiss it. I will give it a go and decide based on that. If I like it, then it could turn into a pleasant surprise. If I don't like it, I won't ruin it for others by vocally expressing my dislike at the end of the attraction, I'll just come here and say that it wasn't all it was cracked up to be, at least to me. People are there on vacation for the most part and want to be able to enjoy their time, not get someone else's displeasure with a replacement forced on them.