For me the biggest advantage of line contact over conical and elliptical is lower IGD and maintenance of HF level at end of record. Especially the latter! This is the main advantage of CD over vinyl AFAIC. The best line contacts (Shibata, Microline) do away with this problem. The record sounds the same all the way through - inner tracks do not sound less crisp than outer tracks. Not so with conical and cheaper ellipticals.
Is elliptical the best stylus profile
In my experiences, it seems that elliptical shaped stylus track better and pretty much have the same amount of detail that a line contact has, maybe a little less. The difference, again in my experience is that the line contact needs to be set up perfectly for good performance. How many of us are experts at setup. Cartridge manufacturers, Why not just use elliptical shape and give everybody a break?