为什么设置ANSI_NULLS对比较字段无效?

I would consider SET ANSI_NULLS OFF mode very convenient and would use it by default if it worked consistently - allow to compare nulls using = or != everywhere. But it works only if if I compare to explicit inline null, but if I compare to a field that contains null - it DOES NOT WORK. Why would Microsoft design it like that ? No wonder why nobody uses SET ANSI_NULLS OFF mode by default. I'd rather stay with pain of "is null" and "is not null" than think about what I use inline and what not.I would consider SET ANSI_NULLS OFF mode very c