In any case, I think engineers should in general do more creators work and product people should focus on keeping the business alive. Indeed there must be people that know the market, the business implications and the competition.
However, in my experience working on a big product with multiple teams, the main problems with devs getting creative is
(a) the consistency of the user experience suffers badly
(b) the overall architecture erodes as everybody builds particular solutions fitting their specific problem
I am not sure what the best way is to reconcile Dev happiness and (a,b) in this context.
Anyway, one could solve it by maintaining a ratio of people with a lot of experience.
(a) A Designer needs to be on the team that can do a Corporate Identitiy (CI) => this way it's possible that Engineers create their own Bootstrap
(b) Either solve it top-down by having an engineer with enough architecture experience; or have architecture guidelines in place / develop them consensus-based
At most places there are very concrete guidelines about codestyle, usually ensured by linters. One can also put more emphasis on architecture style