What's up with the doubled pawns? There's another question on this SE, which asks the question in reverse:
What are the reasons why I should not try to take a Knight with my Bishop if it&#39;ll result in doubled pawns?

The answers do not adequately address, why you should try and double up your opponents pawns. To be more precise let me point to this Youtube video explaining 
the Budapest opening.

[fen "r1bqk2r/pppp1ppp/2n5/4P3/1bP2Bn1/2N2N2/PP2PPPP/R2QKB1R b - - 0 1"]


The Youtuber recommends ...BxNc3 with the sole aim of creating doubled pawns. So why are doubled pawns so awkward? The only reasonable answer on the Wikipedia page I could understand was that the Rooks can't provide support to the leading pawn in a doubled pawn structure. Can someone shed more light?
Isolated double pawns like in your example are considered to be both a static and a dynamic weakness. It is a static weakness since the pawns can no longer defend each other or be defended by other pawns. It is a dynamic weakness since the front pawn is blocking the advance of the pawn behind. It is strategically important for the opposing player to control the square directly in front of the pawns, c5 in your example, thereby cramping the movement of both pawns.

However, doubled pawns are often compensated by other dynamical factors, like open files for the rooks and long diagonals for the bishops. 

In the Budapest line you are asking about, the move 6.Nbd2 is more popular (than 6.Nc3), leading to a good position for white by simple means.