Yahoo mobile email

Nokia and Yahoo announced that a range of Yahoo services will be made available on a select range of Nokia's Series 40 non-smartphones. Initially, Yahoo Messenger and Yahoo Mail will be mounted on Nokia's 5300 and 5200 youth orientated handsets, as well as the new 6300 slim handset announced yesterday.
I find it odd that Yahoo doesn't make a downloadable client available to all handsets that were manufactured post Nov 2002.