The website does only have the option of economy or business but when you put in your travel dates and select search you then have the premium service ugrade option
Yes, this is just a recent change as all three classes could be selected when selecting dates. Wondered if they were dropping the prem econ service.
AFAIK the prem econ and econ seats are exact same pitch on the Icelandair and Neos aircraft, perm econ only entitles you to extra baggage, in flight meal, check in and IFE.