I'm not sure what you found heavy about it; it's feature-full, yes. (I'm a bit familiar with the code because I used it in a project of my own and have my own fork of it at GitHub.)
well, for one thing, one of its modes is to launch a background thread to perform a user-specified operation while it is being displayed. not something a control should be doing.
That is just one of it's modes, and while in theory I agree with the separation of concerns, the cognitive overhead of coordinating the control with the worker thread vs letting MBProgressHUD manage both is substantial.
It's a fairly small addition for how much poet it gives. I agree that it's not for everyone.
http://www.platinumball.net/blog/2010/02/27/uiprogresshud-re...