I don't really see Data ever having been a "big deal". If he were, surely somebody would have shown interest in him. But no, he's allowed to languish in some menial Starfleet job for more than a decade before Cmdr Maddox makes his halfhearted attempt at doing some further poking on him.
Data was the only sentient android at the time of TNG, but that only need mean that there was no demand for sentient androids at that time. There could have been artificial sentiences galore, occupying other media such as holodecks or computer cores - but only Soong was mad enough to insert one into an android body.
It's even possible that he chose the android form to showcase his true brainchild, the positronic brain: this technology might have been superior to existing computers only in its compactness, and it would then be a dramatic demonstration indeed to show that humanlike sentience could now for the first time be packaged in a humanlike skull.
Alternately, sentient androids were old news, long since proven useless, and nobody but the old fool Soong would consider using them as part of their high tech experiments.
Really, while Data admittedly was unique, Starfleet or Federation science only expressed interest in him when he caused unique trouble. Apart from that, he only held curiosity value to Kivas Fajo, a dedicated collector of generally useless curiosities.
Timo Saloniemi