Why are we going from DUV straight to EUV lithography?
As the feature size decreases, the wavelength of the source and lithography system must also decrease. The problem is after 193nm materials and air are significant absorbers of UV which happens around 157nm. In addition, excimer lasers no longer work well as a source after 157nm. 

So if a new lithography tech requires vacuum, mirrors and a new source, you might as well do it right and jump down to 13.5nm. This step has taken 15 or so years and required entire industries to be developed to achieve 13.5nm lithography, including two EUV steps would be very costly due to the costs of developing an EUV source alone.  



Source, Slide-5
OR
Extreme UV lithography - Electrical and Computer Engineering waterloo 

Some other interesting notes are lenses are too absorbent at EUV wavelengths so mirrors must be used, and 13.5nm sources will need about 1MW to get 200W of EUV light.