Ease of availability of third party repair/replace parts, and due to economies of scale, them being cheaper as well. Also I know that Lenovo will officially provide me the parts easily even 6-7 years down the line, no matter if I am a business or home/personal owner of a ThinkPad. The only complaints I am seeing are the newest fingerprint readers on selected models like Yoga being less compatible, other than that everything is as standard on Linux as it gets.