This is not correct.
With Reiger, M-Sport has been in the forefront of suspension development in the WRC, and still is - tough surpassed by the enormous budget and engineering capabilities of VW.
The suspension in the current DS3 WRC is seen up on as being a little old fashioned compared to the competitors. But the car is still a very effective tool You can win rallies with (as proven by Loebs speed in Monte, and by the speed of the inexperienced Meeke).
Also in the engine departement there is room for improvement, which will come with the 2017 car and the "WTCC-engine."
The DS3 WRC is built around the Loeb-style, or Nose End First or what ever You want to call it, as modern rally cars should be. And by that its faster in the right hands than a car not built for this type of driving (Ford is the car that is furthest from the DS3).
Loeb would be a great asset in developing the DS3 WRC, but I think Citroën wants to prove that they can have a life whit out Loeb, and that they can manage by them self.
They got a huge confidence boost by the WTCC, and the way they dominated the whole series, and off course have high hopes for what they can do in rallying. But they have done to big mistakes in the fight to be future world champions, and thats to close the door on both Loeb and Ogier.
In hindsight Ogier should have taken Loebs place when they had the chance. But everything is easier in hindsight.
To realise how similar the WRC cars really are, and how important the driver is, if we take away Ogier from the 2015 championship, this would have been the winners:
Monte: Latvala, VW
Sweden: Neuville, Hyundai
Mexico: Østberg, Citroën
Argentina: Meeke, Citroën
Portugal: Latvala, VW
Sardina: Paddon, Hyundai
Poland: Mikkelsen, VW
Finland: Latvala, VW
Germany: Latvala, VW
Australia: Latvala, VW
Corsica: Latvala, VW
Catalunya: Mikkelsen, VW
Wales: Meeke, Citroën
This both shows that with out Ogier, there would have been better chances for the other drivers and teams to win, and also how good a season Latvala really has had (but doesn't help when You are competing against a master).