Why are aid workers getting attacked?

 From the NY Times:  news of a 10-fold increase in attacks on aid workers between 1998 and 2009:

Soaring violence in Somalia and Afghanistan helped make 2008 the most dangerous year on record for aid workers, with 122 killed while carrying out their work, a report showed on Monday. Altogether, 260 humanitarian workers were attacked in 155 serious episodes in 2008 — compared with 27 instances in 1998, according to figures compiled by the Overseas Development Institute in London and the Center on International Cooperation at New York University. Most of the violence occurred in three countries — Somalia, where 45 aid workers were killed, up from 7 in 2007; Afghanistan, with 33 deaths; and Sudan, with 19. Local humanitarian workers were most often the victims, accounting for 104 of the deaths. The study also found a significant increase in kidnappings over the past three years. “It’s a very dangerous profession indeed, and I don’t think that’s understood as much as maybe it should be,” said Abby Stoddard, a fellow at the Center for International Cooperation who co-wrote the report.

Someone--whether it's donors and NGOs, the aid workers themselves, the recipients of aid, or all three groups--feels that development aid is important enough in these contexts that it should be delivered despite violence that increasingly threatens both aid workers and aid recipients.