The price is very high.
A new lens mount means consumers spend money buying new lenses. That is the fundamental idea.
It is revenue.
When too many Leica R and M owners hang on to their legacy lenses, the income stream into Leica stops.
Well, the Leica T mount lenses are autofocus. All are made in Japan. (because Germany is way behind Japan in autofocus electronics & manufacture of AF lenses)
Looks like Leica believes in APS C rather than MFT. A better sensor size in the long run.
It may cannibalise the Leica M market. There is an adapter to use M lenses.
This may be a boon for Leica or conversely a "T" for Terrible mistake. See how the market responds.