Also, on a related matter, when a user creates an account, she must specify an email and a username. While I can see that this is useful for forums and other stuff, in a situation where you just want to differentiate users, giving a username and an email sounds like an overkill.
A very astute comment, and I agree completely. YUMPS is being built to NOT require emails or passwords (despite some of the screens), if the administrator doesnt want to require them to create accounts.
There are some sticky wickets with doing this and it involves some interesting choices, for example:
If you don't get an email for a person, you cannot send them a password reminder. If they log out or connect via another computer, and have forgotten their password, and all they have is a local account with password (not a bridged account), then there is no way to send them a new password and an administrator will have to step in and handle it on a case by case basis.
YUMPS is built so that you can let people create accounts and enter some areas before providing an email or password, but restrict others that prompt the user that they need to provide an email/password first. This addresses your idea about needing an email to post -- but i think it will be useful in other cases too, where you want to make signing up as easy as possible, and let the user modify their profile at leisure, but restrict certain actions to only after they provide a validated email.
The modify profile screen you saw that said the user has to provide their current password to modify certain fields -- that actually is only the case when the site has been configured that way -- it would not be required if the site did not require local passwords.
Currently when you create a bridged account you are prompted to create a unique username, which defaults to a uniquified version of your facebook/twitter username, etc.
I will be adding a feature that is a 0-step bridged account creation, which will be suitable for some sites. This is the kind of thing used in blog comments where you don't want to bother the user by asking them even just for their username -- where the yumps account creation is entirely automatic and behind the scenes, and the user never even has to worry about whether a local account was created for them (a unique username will be created automatically for them). Then on those occasions where the user is a regular site participant, if the user ever wants to they go to their site yumps profile and modify their info.
As you can see, the issues you are raising are EXACTLY the kinds of issues that YUMPS is meant to handle well. While user sccount creation and management is a small side detail for most web services -- it is one of the central focuses for YUMPS -- so I intend to make it better and more robust than anything else out there.