No where government of Canada or immigration EVER claimed work permit is the path to immigration.
I agree it is some what odd since people with PGWP and even jobs didn't get ITAs or enough scores.
However, the real motivation to the best of my understanding for the government is to give priority to people with jobs - (this was clearly written in EE mandate) because of all horror stories of educated people being brought to Canada on immigration and failing to find decent positions.
Now the unfortunate consequence of this is, just claiming "I have a job offer" isn't practical.
It opens up too many ways for people to cheat. Hence the best check Immigration could put on this was - LMIA based jobs which PGWP holders obviously do not have and suffer.
But if we go by this logic, there is an even more deserving lot of people (so called) which also suffer.
All LMIA exempt positions (including those who are Post Doc researchers or professors at universities) as well as specialists at big name companies which are generally far more qualified and experienced than a mere Canadian fresh grad, also do not get that 600 and hence are treated the same way.
To me, the above category is even more under represented this way since again they are working on positions that already didn't have qualified Canadians - which is why those roles were exempted from LMIA in the first place.
But i hope CIC and government would also realize this eventually and get around this.
Moreover, the 450 barrier was broken already (kind of) and most of PGWP holders would have made it when scores came down.
Scores started going up again since the addition of PNP's since those contain even people who are abroad but still applied in time with the basic requirements of the province and got through.
These are some of the imbalances created via this system which i hope CIC would improve with time. But overall i believe it is a good system of faster processing and prioritizing skills that are needed / already established in Canada.