Andalucía always hosts at least a couple of stages, so there's a political motivation to select them. The Andalucía guys are often willing to animate the race on days when nobody else will - long solo breakaways in pan-flat stages because nobody else is prepared to go up the road in sweltering August heat. They had Tondó as a leader in 2009, and he was in form after being 2nd in the Vuelta a Burgos (the Vuelta's main warmup race) but he got hurt in the Liège crash, lost time, and eventually climbed off at the end of week 2. They've continued to look for people who will give them a bit more than just a break-of-the-day position, but the problem is anybody who is on the way up will soon leave for a bigger team (Tondó), so they're often left with their only GC threats being riders whose best days are behind them (Gómez Marchante). Looking at their roster this year, David Bernabéu is the nearest thing they have to a GC threat. He's been 2nd in the Volta a Portugal the last two years, but he's 35 and has been in Puerto-induced exile for four years (and he also tested positive at the 2003 Paris-Nice for those keeping score at home).
However, not every team has to be involved in the sprints or the GC battle. There are places for the teams that enliven the race, and if hometown support and suicidal breakaways are one way to do that, then fair enough. You never know when one of them will work anyway - Oleg Chuzhda taking advantage of the péloton's unwillingness to help Palmeiras Resort chase down the break in Portugal last year, to win solo by more than a minute, for example, or Julián Sánchez Pimienta's mountain escapades in the '09 Volta a Catalunya.
Speaking of Chuzhda, he'll be one of Caja Rural's hopes for an invite - they don't have any stronger GC bids than Andalucía really - they've been continually linked to Constantino Zaballa, but even if they do sign him, is he really much of a GC threat? They'll contribute to every breakaway though, which will sell organisers on them.
Ultimately, the Tour feels far less French than the Giro feels Italian or the Vuelta feels Spanish. And is that a good thing? Should we aspire to the races losing some of the unique flavour that their home gives them? For teams like Andalucía, the Vuelta is their year. They are part of what makes the Vuelta what it is, for better or for worse.