In brief: Let’s not call this group a state.
The term “Daesh” is strategically a better choice because it is still accurate in that it spells out the acronym of the group’s full Arabic name […] Yet, at the same time, “Daesh” can also be understood as a play on words — and an insult. Depending on how it is conjugated in Arabic, it can mean anything from “to trample down and crush” to “a bigot who imposes his view on others.” Already, the group has reportedly threatened to cut out the tongues of anyone who uses the term.
Why do they care so much? The same reason the United States should. Language matters.
Source: Words matter in ‘ISIS’ war, so use ‘Daesh’ – The Boston Globe