If ESO doesn't restore window position when you close the game, then it's not user friendly to say the least, but I guess nobody in Zenimax plays in a windowed mode, so they have no idea what you are talking about
Maybe you can report it as a bug. Meanwhile your only option is to do it externally, e.g. via
AutoHotKey with this script.ahk:
Code:
Run eso64.exe
WinWait, ahk_class EsoClientWndClass
WinActivate
WinMove, 200, 100
Place it in the same directory as eso64.exe (otherwise it won't work that easily) and create a desktop shortcut for it, if you need.