It was developed with years of efforts and in 6.5 Microsoft got it much right.
However just because Apple's marketing strategy worked really well, it didn't mean you needed to scrap your well built-in well tested platform in favour of a copy of iPhone called Windows Phone. It has so far not been able to create any excitement in the market yet but on the other hand Windows Mobile has a lot of fans.
Windows Mobile has thousands of useful applications which help so many people around the world. On the other hand, Windows Phone is just a new platform: do you really think scrapping away will convince those hundreds of thousands of Windows Mobile users to upgrade to something on which their favourite apps are no more available?
You need to encash the already built hype and following rather than pretending that you don't have anything at all and starting all over.