I have nothing against 2 Stroke engines, and when I buy a trimmer, it will obviously have a 2 Stroke engine, as I don't have money for those new "Mini 4 Stroke" things, but in a mower, I wouldn't want to be mixing oil and fuel.
Plus, I prefer the low pitched noise a 4 Stroke makes, rather than the high pitched scream of a 2 Stroke.