ioannis , what you say is correct esp for core 10 and 14 chips who's architecture is not particularly c orientated . pbp is hard to beat for small efficient code on these chips.
but for floating point work and/or complicated string parsing on pic18's c comes into its own . I firmly believe in horses for courses and lets face it the difference in price between a pic12f1822 and a 18f45k20 is not that great. as I have said before why struggle unless you are going to make and/or sell heaps of units , most of my stuff these days is one off , plus If I can get the esp8266's to behave the IOT becomes a reality . the esp8266 prg is 8.67k compiled with c on a pic . I will port it to arduino and compare. so far I can't get it to function properly with pbp3 the inherently blocking behaviour of basic functions is making life hard for that idea ,but worth pursuing for the IOT revolution (if its not all hype)