About reinstalling the game: Yeah in most cases this does not help at all but somehoe "eases the mind"
Kind of a "placebo".
Crash at login screen can be any addon causing an endless loop, or any savedvariables file which is corrupt as you crashed to desktop and the files were not updated properly, orthey got too big meanwhile (too many characters in them).
Maybe your antivirus or firewall block some folders in <your users harddrive letter>:\users\documents\elder scrolls online\ meanwhile and thus write protection is enabled and crashes the game. Check your antivirus whitelists.
Maybe even Minion did not update properly and left some half-empty addon folder (only extracted half of the files properly).
We even had it happen that files were extracted but only were at the size of 0kb or half of the files were missing...
I'd always disable all addons and try if it works first!
If it doesn't:
Close the game, backup the files /live/AddOnSettings.txt and UserSettings.txt
Remove them afdterwards.
Remoive the file shader_cache.cooked (no need to backup at it will be rebuild and only contains the textures cached).
Try again then.
If it still fails:
Close the game, check in your live/SavedVariables folder for ZO_*.lua files and backup them, then remove them.
Try again.
If this all does not help remove the total AddOns folder or rename it, and try again.
If this does not help remove/rename the total SavedVariables folder.
You can also check the SavedVariables folder for the last changed files and their size. If some of thema re really big (like 5-10 or > MB) try to rename them so they will be rebuild by their addons (the name of the SavedVariables normally is the name of the AddOns/<folder>).