True, you can keep going to the nexus sites to get your mods. I've never been a big fan of the workshop when there's already long time established sites like the Nexus that have more modding possibilities than the workshop. The system could work if it was implemented right.
The problem that lies here is that Valve is trying to fix something that isn't broken. Modders for a long time in the TES community have had donation options and people use them. Valve is taking 75% of a donation for something they had no hand in. Players that buy a mod get a one day grace period to get their money back no questions asked. After that, you're out of luck. Valve says "please ask nicely for the mod to be fixed" to those who find themselves outside the grace period. To me, that's unfair.
Also, if you have ever downloaded a mod from the Nexus, you'd know that some mods are based on others. If someone is making money off of a mod that requires the use of another's mod, shouldn't the other guy get included too? There's also been quite a few people that have had their mods stolen from the Nexus, uploaded to the Workshop, and then had a price tag put on them.
Anyway, it's a very complex issue. If you want a rundown of it, watch TB's video. He does a good job (as always) of explaining the situation.
Also check reddit. Seems like they have a second by second update to what's going on as some things have changed since Valve announced the system.