This is not such an advantage, WML was never successful and it is going to be replaced (replacement is in progress). lack of support for a standard display content and format, low speed in processing by WAP phones, communication and processing overhead, lack of support by service hosts, also there are so many wap phones in comparison to supporting web  browsers and hosts, etc,

how many people are really using the wap service?

personally I don't see WML support to have a huge added value, these communication and formatting are in the process of replacements,