I essentially agree and i love a well done ableton/traktor set but i still think it's got ways to go as far as sound quality is concerned, and traktor/ableton mixes also tend to feel really stiff compared to nicely beatmatched mixes. Unless something really drastic happens, tempomapping/timestreteching/warping will always mean a loss in sound quality and i'm not a fan of how it tends to lock everything with an iron grasp to the tempo. its convenient but not very funky. Also, the fact that all the music (more or less) is being done on computers with digital plugins now means the highs are harsher then they were a decade ago, timestretching will only make this worse.
If you've got your gear in order, like summing through an allen & heath or something and knowing what fx generate evil highs and things like that, you can get things sounding pretty decent. that almost requires sound engineer/producer level skills though and most laptop djs wont have those. i've seen quite a few laptop sets that really fell short and i think we'll be seeing more of those in the future untill either experience or technology fixes that soundquality issue.