Everybody is having there own personal choices so if roger is in favour with his bitcoin cash and want to promote it like crazy. To be honest everything is related to the profits and making the wallets fat when it comes to the crypto currency! (Yeah unfortunately). There is no one who is behind the development of bitcoincash or any other crypto currencies so it would be unrealistic to say that in first place.
Any big investor wants to advertise bitcoin just like him. If the bitcoin is more noticeable, the more chance to invest bitcoin. Capital is being poured into bitcoin
Bitcoin and BCH are different things. Bitcoin has already achieved the state of saturation where it does not need anymore attention. It is getting noticed automatically because its bigger and famous already. :-)