Reading back over the last few pages I honestly don't get the complaints claiming Dany is wasting time, or listlessly twiddling her thumbs through the desert. Freeing slaves has been an integral part of her arc since season one, directly responsible for her greatest losses and triumphs. Beyond the sentimental motivations what she's doing is strategically brilliant, bolstering her ranks while allowing her untested army to amass invaluable battle experience.
Dragons are a big deal but dragons aren't invincible, and her's are half sized. The show hasn't been shy about letting us know it could take years before they're fully grown. As they age, what better use of her time than to build a military force large and seasoned enough to realistically contend with the armies of the Seven Kingdoms? Further, given the state Westeros, starving & war torn with more threats looming, as stories of Daenerys' exploits drift across the Narrow Sea how long will it be before the people look to her as a saviour, and begin pining for the Dragon Queen to take the Iron Throne?
