How sad Trev - and in such a short time! Mind you, what you say about most shows being actors aided by puppets is very true for puppetry generally. Certainly if you go to a festival in Britain 95% of the shows will be of a similar ilk. There's an awful lot of so called table top puppetry - and a lot of so called Bunraku style - a couple of puppeteers dressed in cat suits playing with a doll and pretending we can't see them. It takes the genius puppetry of War Horse to really make puppeteers invisible.
The causes in Britain are similar to what you surmise is the case in Poland - frustrated actors who can't find jobs fall back on story telling with puppets for children as the only way to satisfy their craving to perform.
Even so, you say Krakow, Lodz and Warsaw etc still have their puppet theatres. That's good. Liverpool, Manchester, Edinburgh, Glasgow etc. have never had any sort of regular diet of puppetry, because we haven't much of a puppet tradition at all.