There are plenty of problems with the workshop model as well:
- If a modder deletes his mod, it gets deleted from your local computer as well unless you went the extra mile to backup it. This will mean that any save games that depend on that mod will not work after the fact and there's nothing you can do about it (unless you happen to able to locate and source the same mod with same version elsewhere).
- if a modder updates his mod and it happens to now suddenly be incompatible with another mod your save uses, again, your save game that depended on that now incompatible mod will not work after the fact and there's nothing you can do about it (unless you happen to able to locate and source the same mod with same version elsewhere).
There's a lot of upsides of workshop but it's not a perfect system which is exactly why I hope TW will have their own mod manager that simply integrates into workshop in the steam build.
There's nothing that beats a real purpose-made mod manager that the devs themselves designed and wrote. They can have a lot of safeguard systems in case of hickups such as having local copies of the mods in any recent save games or having the modders tag their mods based on game version, other incompatible mods or mods that they require to work properly.
I do hope they have a full-fledged mod manager.