Wrong. They could have entered coalition with PO instead - but Kaczynski's maniacal desire for control prevented that. If you look back, everyone expected a PO-PiS coalition - but PiS demanded control of all the "security" ministries - which was understandably a deal breaker.
It was the one thing that single-handedly destroyed PiS - the utter shame that was Deputy Prime Minister Lepper alienated most of the centrist voters.
PiS's win did not assure a majority government and a minority government was extremely difficult and involved begging for support in parliament before every crucial vote
Minority governments can be very successful if the Government pursues a policy of ruling by consensus. The Scottish Government 2007-2011 was an excellent example of this.
Marcinkiewicz was also fairly popular - if you speak to many PO supporters, they'll tell you that he wasn't a bad guy. But obviously - he started to pursue his own path contrary to the wishes of the Dear Leader, and so he had to go.
Merkel also entered a coalition with the lefties all true Chrsitian democrats despise, because she had no other way out. That is how politics works.
Merkel could easily have gone for new elections, too. But the Grand Coalition was on offer, and represented the will of the German people at the time. As for "despising" - what rubbish. The CDU and SPD are centre-right and centre-left respectively - there was enough common ground to reach agreement.