How can it be more expensive to make?
Easy. This is Hollywood and suits cost money. Youve got development meetings to cater, focus groups to pull together, youve got to go out and hirer another executives sisters former boyfriend to write a song, theres the trip to London for the MacDonalds Happy Meal executives, artist after artist to go through until you find the box cover art that really sells the movie, and then theres that really fabulous premier party to throw for all the executives in the division. The tinsel in Tinseltown has nothing to do with making a movie but it costs huge amounts of money.
The other way is to give a person with a great idea and passion the money to actually make the film. Every penny spent (and a lot of heart) ends up on the screen. In the end, people who see working on a film as nothing but a job treat it like a job. People who see working on a film as fulfillment of a dream treat it like that. No one is going to plop down $7.50 at the box office of $19.95 at the store because some forth level creative executive had his car waxed on the films budget the audience pays because of what they see.
As for just making a quick buck from sequels, isnt the magic of synergy being able to spread a product ACROSS the company movies, television, parks, merchandise instead of going deeper and deeper down the same path? It seems that keeping a family at WDW longer to watch The Lion King show makes the company more money than trying to con them into buying The Lion King 17 Timon and Rosie Together Again At Last for $9.99 at WalMart. And even sequles fail to fill the coffers after a while. When was the last time you saw a 'Batman' movie?