I don't understand what peoples issues with having a sealife centre an attaction like Alton Towers which is a place for the whole family needs rides and attactions for the whole family and a sea life centre fits that bill perfectly as not everybody likes rides and is something the whole family can enjoy and is something else the park can use to entice people to visit the resort over other visitor attractions.
At the end of the day we would all like to see big new coasters and and thrill rides each season but the park need to attacted all different groups of people, the park aren't stupid and complete their research so know what they need to add to attact guests thats part of the reason we have not seen any new thrill rides in recent years and research showed they needed kid friendly and Family rides/attactions (much like six flags are doing now). For the park to be sucessful they need all types of rides (obviusly different at thorpe, chessie and legoland being all focused on different groups and thats why they don't get as many visitors per year as Alton which has to attact all groups of people that would visit those three parks).
If the park want to be one of europes top resorts (which they want to be) they need to show they offer a complete package for all guests and value for money for all guests and an attraction like a Sealife fits the bill perfectly and expect to see more attactions like this in the furure (and same reason going to see an increase in shows and on park entertainment) if you visit some of the worlds top parks such as Disney, Universal, Bucsh parks and europes big parks it is not all about the rides, its also about lots side attactions and shows/entertainment. Plus the BBC article stated that it would be a sealife centre with an alton towers twist (likly to be pirate theming).