Both weapons have different uses, comparing them .. to me.. isn't a valid reason to choose one over the other. The tactics for them are completely differwnt, say I want to slow someone down.. obvious Ion cannon.. but if I want a 360 degree firing area, regardless of range.. take that blaster turret..
Tactics, it's what you make your decisions on.
To me it's comparing apples to oranges...
The blaster turret is ALSO Range 1-2. Same 360 arc, same range.