To understand my question better, let's consider the priciple behind the lift generated by the wing - The upper surface of the air-foil is curved to deflect the air downwards using the Coanda effect. According to Newton's 3rd Law, an equal reaction is produced by the downwards deflection of air in the form of lift.
So here's my question - Why aren't some planes designed to look like a massive cross-section of a wing from the side? e.g. A Cessna C172 looks like an inverted wing (with the curved side on the bottom, which might create 'inverse lift' by pulling it down. From that aspect, is the Cirrus SR22 and the Cessna TTx more lift-friendly? Their upper part of the fuselage is relatively more curved than their lower part when viewed from the side. Or am I making a mistake - is it due to high-wing low-wing design philosophies?