Fine price for content, I'm in.
I've backed up my current game, so I can easily run my 1.5.97 game whenever I want. Steam doesn't care, it just runs it.
Upgrading from SE to AE costs money this time? For PC the SE was a free upgrade for us to bought the og and LE and that had a bigger jump than this, the fuck bethesda.
AE is basically two parts. One for everyone, one is optional.
The first part is the update to SE itself, which is a (supposedly) improved recompile of the game (back end improvements, etc). It comes with 4 pieces of CC, including a quest one. This part is free, just like SE was.
The second part is the AE bundle, which is all CC to date - an estimated "Most efficient purchasing" price of about $140 separately. Quests, weapons, armour, spells, etc. Again, optional.
If you don't want it, don't let the game update. It's not like you haven't been warned. Nexus Mods even did a whole fucking news article on it and included a guide to keeping your current setup.