If you listen to the Audio commentary, Lukas wanted to include something that showed off R2 becuase it was really the first chance that they could do almost anything with him...
They tried to make him look cool, and show he could take care of himself as marvolo said, by doing the scene.
Thinking further on it, it presents a large problem. If I remove that portion, then I'd probably have to remove all the shots to R2 still in the hangar. If I did that, then we might wonder why R2 wasn't responding to Obi-Wans summoning. .. so I may end up leaving it... although I see both of your points about the scene...
I kinda explain in another thread that Episode I is split into three sections.
Part I is most like Episode I in its jovial, good guys being good and happy portion of the film.
Part II is most like Episode II and is about the Love relationship between Anakin and Padme.
Part III is the dark part where Anakin Turns and then setting up the for Episode IV.
As such, some parts in Episode I and Part on of Episode III seem somewhat jovial and this is just that. In the commentary Lukas states that it was really the only time he could do something with R2, which he wanted to do badly and felt the fans would want. He wanted to do something with him before it got dark and the tone changed which would then render it inappropriate.