I think prepackaged beats can be useful. Firstly, if you're just starting out with making music and have no idea how a beat is constructed, it's very useful to be able to look at a MIDI beat and figure out what's going on with the kick, hats and snare. Sure you could "learn to play the drums" but not everyone has the means, time or space to do this. Everyone has to start somewhere. 

I remember in the early days of drum & bass music, or "jungle" as it was called back then, almost every track was built upon a sample of a drum break in the middle of The Winston's "Amen Brother." It's the classic break beat, and everyone who was messing around with beat based music at the time would at some point attempt to program their own version - let me tell you that's a hard feel to get down if you don't have a drummer's ear! So even back then in the early 90's there were people swapping floppy discs with MIDI files of these break beats. If you have any artistic credibility though, you wouldn't use these beats "as is," you'd mess around with them and twist them into your own thing. I think that's what a lot of people do with prepackaged beats these days. I've got some of the Groove Monkee ones (played by a real drummer) and they're excellent to use as a starting point. You can tailor them to your needs, requantize them, chop them up, add to them, subtract from them etc. 

I'm not a drummer and I don't have a clue how to drum. So for the time being I will use prepackaged beats from time to time. I don't think there's any shame in it. Long term, I'd like to be able to finger drum like this guy: 

http://www.youtube.com/watch?v=0K2aynMMBpo