Tobi doesn't even use his advanced Sharingan version, he can do his stuff without using the MS

also

Itachi's MS isn't his own either, he got one eye from a friend (see flashback)
if I'm not mistaken, his own MS is that special illusion-jutsu

and I wonder why Tobi has the Rinnegan(?) if he is not really going to use it, or did he just grab it to get knowledge about the techniques he required