[JCD]

Here are some benefits to a line array that I can think of:

1. They are usually super efficient
2. They are supposed to be more dynamic -- if the drivers don't have to work as hard, they should be able to get "there" quicker
3. The crossover, if there is one, is in a fairly non-sensitive region. I'm building (well, I'm currently stalled) a line array and my high crossover point is going to be somewhere around 5k or higher.
4. Reflections from floor and ceiling are minimized
5. Provides a wide listening area

Here are some technical papers I've found:
Link 1
Link 2

Note: the design principles in the first link may be dated. I've been told by someone with more brains than I that the idea's are "OK", but have been superseded for some of the issues presented.

JCD