I have two reasons:
With this project we can improve on bitcoins technical aspects making it more efficient to its users.
Appeal more to a local demographic
Bitshares already has bitGBP, which is pegged to the real GBP. Why not join the community and spread awareness of this already existing solution, rather than trying to create your own?
https://bitsharesblocks.com/asset/orderbook?asset=GBP