[AYBABTME]

Perhaps completion is not the most important thing, but surely it is useful - or not detrimental. It's something that, for some languages, can be done automatically by your computer instead of yourself. I'm all for the computer doing stuff for me. Be it so small as finishing the method name so I don't have to type it, listing the method set for me so I don't have to look it up.

The more the computer does, the better.

of course some argue otherwise, usually blaming IDEs as being a crutch for poor programmers. Surely it can be, but otherwise I say it's a very convenient tool.