It's all about choice and financial freedom. The choice of whether I HAVE to go back to the job that I loathe, or the job that I am meh about. If I have enough money not to HAVE to work again, my choices and freedom are infinitely greater. I can try new pursuits, without having to worry about chasing the dollar.
Good post. OP, I think you may be missing the "FI" part of "ER." Being financially independent is something that can give you a lot of choice.
For me personally, I've had a lot of twists and turns in my young career as an attorney. I lost motivation early in my career when things weren't going the way my employer said they would, I almost got fired a year ago, then things went great, then I had an interview with a big firm (didn't get an offer), and now I'm here plugging away. I'm really tired of the corporate politics and being dragged into matters I don't want to do.
I could go on and on and on about why I don't like my current firm and my current practice, but luckily, I've been saving A LOT while I've been here. This is giving me a ton of options.
In that light, I am really starting to lean towards starting my own practice, maybe even by early this fall. Saving and being smart with money has allowed me to do this much more quickly than if I lived a traditional-spend-90%-of-your-income lifestyle. In fact, I should have about $35k saved in cash by August. We also have equity in our home and almost $75,000 in retirement accounts that could be drawn upon in case of an emergency.
More importantly, my fiancee and I have structured our finances so that her income alone takes care of all household bills. This gives me a lot of flexibility in accepting or denying clients, which I believe is the key to gaining satisfaction from a legal practice.
Thus, by aiming for FI, I have created my own safety net to allow myself to pursue something that I would not have been able to pursue if I had not been saving.
Bottom line, it's not all about early retirement. It's about giving yourself options and choices.