Hi Markus,
I agree with you, but MASS is something very straight forward, plus, don't support paralelization, so if you want to change a smalll amout of data or you really don't care about performance (I mean for the process is the same if the update takes 1 or 4 hours) and the changes doesn't imply a business logic, the user has all the control of which fileds should be changed and for which value, then it's a good option.
But when extra logic is needed, Mass can become a nightmare, I will write a blog about this if I have the time. 
Cheers!
Luis