It is an ego boost thing they do and heck...some of us guys do too.
The whole notion is to give yourself options. It is dating...that's what they do. Now if in a committed relationship that crap were to occurr...well then move on in a hurry.
As for the comment about dating moving to mostly all texting.....truth! But in a way this is a positive thing. The girl really knows nothing about you. Thus you can't really lose points. Which makes it an easier endeavor to hit the poon. Think about it, attraction usually fades the more you learn about someone right? If all you do is text it is pretty hard to F it up. Again...this is dating...not relationships.