The first park has only just opened, or not even opened yet I can't remember. Why would they need to improve it first?
IMG Worlds of Adventure opened in August, I went there in October (heading back for a school trip next week) check out my Trip report.
Well I was referring to building new attractions there, rather than build another park. It seems as though it is a way to make a lot more money like a certain Ferrari World
I believe IMG Worlds is opening up another park to make it seem more like a resort. This is probably due to competition from Dubai Parks and Resorts, which have 4 attractions (with a 5th being Six Flags on the way) to offer in one area. IMG has only 1 park to offer currently and if you look on a map, its quite a drive away compared to Dubai Parks and Resorts, offering more things to do with another park, will make people want to make a trip over to IMG.
In terms of improving the park, for me IMG is the best park in the UAE, sure all the parks coasters are cloned ones, but they are excellent clones. IMG have said that they want to try add something new to the park every year, so no worries on new things there and they have enough time to do so as they haven't stated when the next park will open and will take a few years to build. The theming inside the park is awesome (especially in the Lost Valley section), awesome rides and compared to the other parks, this park has heart. The developers wanted to make something special, (unlike others that just want to sell toys and fast cars) sure 2 areas are based on IP's, but they looked at what made those special to people and delivered (especially with Avengers: Battle of Ultron, which is probably my favourite dark ride).
Also Ferrari World does and doesn't really fit into this. Ferrari World will probably make more, just because of Formula Rossa, but its in a completely different city. Ferrari World is park of the Yas Island group, another themepark rival group with Ferrari World, Yas Waterworld and the upcoming Warner Bros Park under their belt. So once again it makes sense for IMG to expand so they have a chance of surviving.