* Configuring emacs still requires learning a lot about emacs (which takes a lot of time).
* These vi/vim emulation modes doen't touch SLIME's keybindings, afaik. So, to make them less finger-twisting will require manual rebinding (which takes yet more time).
* Most emacs tutorials assume you're using the standard key bindings. So you still have to learn them.
All of the above make the various vi/vim emulation modes fine for people who already know emacs, or who are willing to sink a ton of time in learning it and reconfiguring it. But they are far less attractive to vim users who already have a nice environment set up in vim and feel comfortable in it.
I guess they're still better than nothing. If I had to use emacs, I'd certainly use something like evil mode. But evil mode alone is not enough to make a vim veteran feel comfortable in emacs.
