Amazing what a difference a bit of floor-spacing makes eh. LeBron and Wade can just wreak havoc with even competent 3pt shooting. Just imagine if they'd picked up, say, two or three Steve Novaks or Matt Bonners rather than Miller or Battier. Hollinger had a good line about how Riley has an irrational devotion to (perceived) hard workers like Zo or Haslem or Battier rather than players who are demonstrably productive but maybe don't dial it up to 10 in practice or on every single play vs the Raptors in mid-January...it explains a lot, really. Overpaying for sheer grit is good for the culture but doesn't necessarily result in a well-built (i.e. varied and flexible) team.
Well, Miller and Battier were meant to be the floor-spacers. They both had good career 3P%, only to crater when they joined Miami (though Miller's bounced back this season). Plus they were meant to bring some other skills to the table, like defense for Battier and auxiliary ballhandling from Miller. One-dimensional shooters like Novak are sometimes deemed not worth it by pretty smart people; in Tim Legler's last season he hit a couple big 3's for the Spurs in the Finals and an international reporter asked Pop why he didn't play Legler more, and Popovich looked at the guy like he was an idiot.
The problem for Miami isn't that they didn't try to sign shooters, but that they overpaid for older role players who couldn't live up to their reputations, like when the Cavs signed Donyell Marshall, or when the Hornets gave James Posey $24 million after his year with the Celtics.
The Spurs, meanwhile, manage to find good shooters who are dirt cheap, young-ish, can contribute in other ways, and can compliment their (youngish, cheap, contributing) big men. But any time we talk about how the Spurs run things compared to other teams it feels like we're doing Goofus and Gallant.