Deviate from canon and I won't bother watching.
I don't mind if it improves the story.
And if it has some decent explanation. Look at Star Trek: they massively changed the canon for The Motion Picture by changing the design of the Enterprise. The Enterprise was changed IRL because the producers wanted a snazzier Neato Keen New And Improved Design. But in the in-universe explanation, they had a perfectly fair "it went in for a massive overhaul and refit."
But then STD/SNW changed the design of the Enterprise for much the same "because we wanted to" reason, but did not - and in fact can not - explain the changes in-universe. Which is dumb, because the Enterprise could have *easily* retained the canonical design and yet been made to look fully modern and awesome.
View: https://www.youtube.com/watch?v=NQHvhuNXvV0
I study industrial design, real and imagined. Before the original Star Trek, rocket ships were tubes with a pointed end and flame coming out of the other, with few exceptions. When I first saw the Enterprise I was amazed. It looked right. And the explanations for all of the related technology seemed right. It was plausible. The rest of the tech, human and alien, also seemed right. My first look at a Klingon ship saw a plausible design that fit the overall design pattern - simple, elegant, menacing. This level of design consistency is very important.
Unfortunately, creatives are not at the top of the ladder in Hollywood. Producers are. Some have a little creativity, many don't. But since they are funding the TV show or movie, they get the final say. They look at large sheets of paper called storyboards. These are black and white comics that show key scenes before any camera work is done. As they go through these, the first comment for scenes that show elaborate detail is: How much is this scene going to cost me? This can be followed by an order to cut out certain details. In the case of ship design, it can boil down to personal taste or an order to "upgrade" a perfectly good design or an order to 'give me something new.'
Keep in mind, to Hollywood, movies are made for 3 types of audiences:
1) The average moviegoer who may never have seen a previous Star Trek movie or TV show.
2) The casual viewer who has seen some previous Star Trek but cares little about canon.
3) The nutballs who live and die by canon, and if something has been changed for no good reason, results in rants and raves on the internet...
Doing good vehicle and spaceship design is hard and requires a lot of skill and knowledge. I scan various sites for good SF design and most of it is bad to really bad. A friend bought a $200 Ralph McQuarrie book that showcased his design work for Star Wars. First, everything about the book itself was impeccable - the printing, the binding. A look at McQuarrie's background reveals a few things.
"McQuarrie initially worked for a dentistry firm, illustrating teeth and equipment,
[1] before working as an Artist and Preliminary Design Illustrator for the
Boeing Company, where he drew diagrams for a manual on constructing the
747 Jumbo Jet, as well as designing film posters and animating
CBS News' coverage of the
Apollo space program at the three-man company Reel Three.
[2][3] While there, McQuarrie was asked by
Hal Barwood to produce some illustrations for a film project he and Matthew Robbins were starting.
[2][3]"