Poppy, you're spot-on overall. I'd like to make some suggestions and responses.
First, we need to recall what it was that really got us hooked and coming back for more, especially in the beginning. Those are the core things that need to be addressed and/or expanded on, rather than introducing whole new mechanics such as shrines. What hooked you? How has that scaled? Poorly
Second, especially for high-level players, there is a discrepancy between hard-to-get dragons (Rainbow, Moon, Sun, Panlong) and easy-to-get dragons (everything else). And that discrepancy is huge. More "normal"ish dragons that are hard to get, such as sandstorm, bluefire, frostfire, would help. So, initially, you have this huge list of neato hybrids to get, then to seem to rapdily switch over to where they all just show up halfway by accident, which takes all the specialness out of them. Meanwhile, you give up in frustration over rares. Needs to be more middle ground.
Third, a huge impetus for enjoying design as you mentioned was seeing others' islands. I spent a lot of time early on visiting random islands and getting ideas and enjoying others' creations. As coin gets easier to acquire, the islands get smaller and smaller. Bigger islands and more themed decorations would make design a lot more intriguing.
Along these lines, the social aspect could be explored and enlargened, really driving that creativity. Either BFS could have a Park of the Week/Day/whatever function, or a Hall of Fame, or something, or perhaps a player could start a blog/site where islands/parks can be shown off, addicts can vote, etc. I know we can post screenshots here, but something more organized and formal would really catch on, I think. There could be in-game benefits for sharing, getting votes, etc., I dunno, lots of possibilities there.
Fourth, though this would seem pedantic to some, more achievements/goals might help folks. To some, achievements are an insult. To others, they really drive you on! And I don't mean just "hatch a blahblah egg." I mean interesting things, like putting certain dragons together, or design-related achievments, upgrading this or that, having only cold habs, I dunno. Weird stuff for fun.
But, yes, things can stagnate quickly. New dragons and associated flavor buildings are fantastic, and need to keep coming! But part of the problem we are seeing right now is that we just had one extremely hard new dragon added (Panlong), which everybody scrambled (and still does) to get. And then a very easy one (Love - relatively speaking way easier than Panlong, with very short breeding/hatching times to boot). So we went from this dogged determination that resulted in cheers of excitement when it finally came (or frustration), to a very easy prize that didn't involve much effort and yields a "meh" feeling.
Finally, more ways to decorate. More themes. Someone suggested being able to spray paint your island with snow, or sand, or whatever, depending on its theme. Wonderful idea! More themes would be great, too, kind of like the couple of asian-ish decorations that came with the Panlong, etc. Could do a set of castle/medieval pieces (decorations <em>and</em> functional buildings), a set of desert/oasis (not just a cactus), a set of winter wonderland, a set of this or that, to really differentiate the islands. Lastly, in this category, variations on the habitats. Maybe you want your water hab to look like a desert oasis, to fit in on an earthy island. Or snowy volcanos for your Oregon mountain island. A Japanese tea garden version of the plant hab. Stuff like that would really set the parks apart.
Just my thoughts. Love the game, love the dragons, love everybody's parks, and love new ways to decorate mine.
