Merlin's attractions basically get off the drawing board and into real life based on their marketability. Take Derren Brown's Ghost Train at Thorpe - on paper, it sounded thrilling and highly marketable but in real life, it was a (insert expletive of choice). However, you can't argue that the ride drew the crowds in it's first few seasons and was highly talked about.
That's the sort of thing they'll be going for with Nemesis. Essentially this project will cost 10+ million quid, and they'll be damned sure that everyone knows it's 'new and improved' - otherwise what would be the point of spending the money?
As mentioned above, it's inoffensive, people won't use the name, but for marketing terms, it gives them something to work the 'new' angle from.