I've always liked that scene as an homage to an almost identical scene from TOS with Kirk. Musically, the tender "Blue Skies" riff, symbolically suggesting that perhaps Data is in fact not really as gone as we thought transitions hopefully into the end credits march with it's bold Courage fanfare over the shot of Enterprise under reconstruction letting the audience know that indeed, one journey may be over, but the next one is ready to begin. It's bad luck that Nemesis wound up being the last Trek Prime movie. It's not a great film, but it's a very good film. It leaves me wanting more. Unfortunately, for good or ill, Trek Prime will likely never be revisited either on the big screen or the small screen.
Shinzon wasn't Picard's nemesis so much as he was the Romulans' nemesis. They needed to play up the "overthrow of the Romulan government" angle and downplay the "Picard vs Evil Picard" angle. Instead of Shinzon being a slave in a mine, (which by the way was incongruous with his also being a great general) who leads a Spartacus-like revolt he needed to be written as a Patton-esque "old warrior" who just couldn't handle the newer, friendlier relationship between the Empire and the Federation. This could have played out in a story with elements of ST III and VI, both of which had similar plot tropes. It makes sense from the standpoint of the "nature vs nurture" subtext of the film. Handled correctly, it would have been interesting to see Shinzon played as "more Romulan than the Romulans". Tie that to the idea I mentioned earlier about Shinzon as Patton/the perfect warrior who can't survive the peace and he would have been a powerful "opposite" of Picard the diplomat and peace supporter.