This is an interesting discussion.
I am a firm believer in good basics, in any area of sport, or i guess life in general.
but don't forget the following:
1)It's natural to want to learn a wide range of steps, even though they might be danced in a somewhat flawed way. Nobody wants to read the same book over and over again
2)Not all learning is just for comps. A wider range of steps adds to the fun of 'just dancing'
3)My experience of working on more advanced steps is that they make the basics seem easier(which i know may be misleading) but they also add to my repertoire of movements
It is important to practice basic steps regularly. A couple of rounds of basic slow waltz before practising the 'real' routine makes a big difference. And if you REALLY want to learn basics well, start teaching them!
I well remember watching a top New Zealand squash player in the 1970s (his name was Cam Nancarrow) in his knock-ups(5 minutes before the match starts). He wouldn't do anything fancy, but he did exaggerate the 'watch the ball' principle. This was his way of working on basics.