Lightning talks are awesome. I sadly missed most of them this year because my Real World Web Scalability talk overlapped a bit.
I wouldn't mind if more of the conference was super short talks like those. Some of the regular talks have me wanting to bite my arm off because they went too slow and too long and just had too little content. Of course there are also many talks that are just perfect for 45 minutes. (Like my scalability talk which is ~40 minutes at full speed which people seem to enjoy ;-) )
I do appreciate the logistical trouble with having more speakers. With shorter talks you can't let them all in for free and then it's harder to make them come and talk and so on.