do not do conversions to float in interrupt callback and give access to ...

...raw integer data.

In some applications you do not want the float data (e.g. if you want to send the data on wireless and keep packets small), so access to integer based data is needed.
Also not converting the data in the interrupt callback but only when the data is queried is probably a performance improvement.

In any case, thanks for this library, it seems much more reliable that the blocking version from Adafruit.