There's a few different reasons (especially depending on the company) why that these happen, but I personally think it boils down to two unintuitive quasi-psychological reasons.
- When suits are fumbling around looking for a new shiny project that'll give them a sense of "legacy" and their fingerpints all over (that won't affect immediate profits), somewhere in marketing and brand is usually the first place they'll grab. If wins, fantastic, they've secured their legacy both in a career-spanning sense and at the company itself with a bonus. If it fails disastrously, easy enough to quietly switch back to the old and to save face by tackling a different project.
- Sort of relatedly, a lot of marketing suits hate feeling "left out" of trends; it's something I loathe about the industry, the hyper-focus and optimization of being at the crest of new trends (when arguably they're usually shittier than the previous ones). Oftentimes their entire salary / sense of purpose of being at the job is tied into with presenting the latest and greatest, and insecure designers will be too happy to be enablers.
(My opinion may be a minority of the industry itself as if it were me, we'd be back to 90's era logos for the sheer zany quality.)