MSE is useless?? nah...I simply disagree with that
MSE is a good Av, yes it's detection is poor among the others, but keep in mind..MSE is one of the lowest false positive AV out there, according to my experience MSE never gave me any false positive result like the other AV does.
"Essential" which means it's really protect the essential thing on your windows, so if a user use it for dodging/catching PUP/PUM/Ad-ware you would likely to be disappointed, but when MSE is used for "protecting your essential OS" then yes it's does the job very well done.
Also...I heard MSE only catch "Live Malware" not some kind of small/potential annoying software, to be honest I don't really understand what is "Live Malware" means..but I guess what "live malware" means is some kind of very dangerous malware that can seriously damage your OS/computer.
So for anyone that want an AV that can give user various result or detecting many things, it's obvious MSE isn't a good choice, but for anyone that don't really understand about computer, or for anyone that want keep things simple,free and protecting the "essential", then MSE is a good choice