People invent new words to avoid the baggage of old words all the time. Statistics has a lot of old associations and negative connotations, data science sounded fresh.
The title "data scientist" was massively overloaded over the past decade, so while it might mean "statistician" on one team, it might mean business analyst, visualization designer, data engineer, or a number of other things that are outside the core skillset of a statistician on another team.
Why is "statistician" not a good enough title? That is what "Data Science" is, statistics.