Floating point math was a key feature on these early machines, since it opened up the "glorified desk calculator" use case. This was one use for them (along with gaming and use as a remote terminal) that did not require convenient data storage, which would've been a real challenge before disk drives became a standard. And the float implementation included in BASIC was the most common back in the day. (There are even some subtle differences between it and the modern IEEE variety that we'd be familiar with today.)