new set of SID/STARs etc had to be designed and tested (plus ILS etc.
instrument procedures).
Most probably ILS procedures were not too hard to design as there is no ILS in WMI at all (despite the promises/plans).
It's the usual Polish airport strategy: built as much/big terminals as you can and don't give a
about how those aircraft will land. Not a single CAT III ILS in a country with a population of 40 million. Actually not even a CAT II ILS other than in WAW.
KRK, GDN, KTW, WRO, POZ, RZE, LCJ etc. are all CAT I. There was not even an approved LVP in KTW/GDN until 2011.