As for the objectives of Zoo's in 2010 they are all first and foremost businesses and they all need to at least turn over enough money to cover their costs. However, like any business profits are desirable... and increasing profits have and always will be something any business (including zoos) will strive for. The great thing about Zoos is that large proportions of their profits are spent on wildlife research and conservation. And zoos are of course, always in a perfect position of educating the general public.
However, to push for profits year after year, any business has to reinvent itself through new products, re-branded products etc. If the Kolmarden dolphin show remained the same year after year, people wouldn't necessarily stop visiting, but Kolmarden certainly wouldn't experience an increase or even steady numbers flowing through their gates. This would affect their profits.
Light, music, clapping and an overall high energy presentation inspires people and make them wanna come back for more. A recipe for success. Inspiration also creates a great foundation for learning.
As for dolphin welfare. I believe Kolmarden has an experienced (ie many older animals, all of which have been in captivity for all most if not all of their lives) group of animals and mixing the routines up for them, challenging them with complex behaviours and keeping the energy high promotes their welfare if anything.
So, if a show like this and 'Disney-style' rides can keep people coming through the gates and the dolphins are 'happy' and healthy, then how could it ever be bad? Add to that the fact there IS educational messages in the show, Kolmarden is one of the world's most successful dolphin research facility and guests can wander over to the lagoon where even more about the dolphins can be found out. I think comparing it to 'Circus' is insulting. Kolmarden know what they're doing and are in fact keeping ahead of the game, not going back in time.