Why would you want it?
They can make them smaller. Because of the incredibly tough, super-thin shell they can make the aids smaller than ever before which makes this aid more discreet and invisible than any hearing aid made previously by Phonak.
The Virto B-Titanium uses the newer Belong or “B” platform which came out in September 2016, rather the older Venture or “V” platform which the previous range of aids was based on. As this is the titanium version of the Audeo B90 you can find the more details technical specs of what the hearing aid is doing here.
Titanium shells are 15 times stronger than the usual acrylic ones and the aids are also particle and water resistant. Having an in-ear aid that is as tough as an over the ear aid is certainly a good selling point for anyone who has accidentally damaged their in-ear aid in the past.