The common level of acceptance for necromancy remains to be seen, but nothing in the lore suggests that it is illegal. Templars do not specifically hunt down necromancers, and I've never heard mention of necromancy being against the laws of the Chantry or any nation. In addition to the various moral arguments against blood magic and its historical importance to the Tevinter Imperium, the Chantry forbids it because of the ability to control minds, the apparent link to demons, and the fact that it cannot be easily negated by the Templars. Necromancy shares none of these characteristics, so while it may be seen as distasteful, nothing about it has caused the Chantry to ban its practice outright.
I accept your point, but as I said, we know so little about the status of necromancy in DA at this stage (barring Nevarra) that we are basically speculating. My point was that given that the Chantry is pretty hostile to anything involving the dead (other than cremation rites), a broad tolerance of necromancy would seem fairly counterintuitive. I suspect, because it has never even been mentioned as being a thing in DA until recently, that it's a more recent addition by the story team to get a around the difficulties associated with having player blood mages, so we know little about the Chantry's views on it. Necromancy would appear to be a compromise option that allows people who get a kick out being the "evil sorcerer" archetype to play their style, without the lore headaches associated with blood magic.
Personally, they seem awfully similar to me and I find it hard to countenance why the Chantry, which takes a deeply conservative view on all things magical (they even forbid Dalish magic and shapeshifting as heretical), would tolerate necromancy. Obviously, Bioware have decided to have it in the game, so they must have devised some justification for it to be at least permissible, but it (to my mind) seems to run contrary to what we of the Andrastian attitude to matter of magic and the dead.