no it isnt. bethesda games are working just perfectly fine with nexus AND workshop. its the modders decision which one they want to use. just as now they can choose between curse, kerbalstuff, or just uploading to mediafire... "What if they want a mod that's workshop-exclusive? Well... Too bad?" so if that mod will not even exists for anybody is better? omg, and the messaging somebody as an option is always there. the fact is workshop has a fantastic versioning nothing else offer. my mods have about 5k downloads and only about 30 subscribers on kerbalstuff. it means only 30 ppl will know if i ever update them. on steam i have over 5k subscribers and for them the game will automatically update the mod if i upload a new version. they dont have the hassle to look up every day if a minor bug been fixed in a mod they use or not. (i've already stopped using curse because its a crap and will probably abandon kstuff too, though its not that bad) ohh, and workshop doesnt limit you in having multiple versions, there are plenty of mods with multiple versions there, it doesnt make configuration difficult, it has size limits more than enough for complete skyrim overhaul, so i think its plenty, it doesnt support modpacks but doesnt block you uploading them and locks out only those doesnt have the given game, imo its a very good system. (if you have bought the game legally you can register it on steam and download the mods...)