I dont know why the US can't make it a bit easier for artists to get visas.. this isn't the first case of this..
Because Big Brother does. not. ROCK!!!.... nor Tango, Waltz, Samba, Boogie or any other worthwhile artistic endeavor.
Seriously though, don't assume that it's because the artists are waiting too long to apply. Often it's because of some other agency, especially the particular embassies, who are the ones holding things up. Sometimes it's some other agency they are waiting on to issue some other documentation needed for the visa. Years ago (well before 9/11), I was a travel agent. One of the more frustrating aspects of that job was waiting on the embassies to issue the visas for travelers. Of course, in my case, it was from other countries so Americans could travel overseas but, no doubt, it works the same the other way around. In fact, MUCH worse now! It was a rule of thumb that the visas were never issued until the very last minute. Couldn't tell you how many very nervous travelers I've had to deal with waiting for their visas to show up for a trip that was to start the very next day. Seems the French visas, more often than others, wouldn't show up until about 3PM the day before the trip! It was stressful for me being the agent and being use to it but I can fully understand how nuts our clients were feeling! So, don't always assume that it's the band who has slacked off.