A big engine can cause problems: it burns lots more gas, resulting in higher operating costs and a shorter range (relative to a smaller engine on the same plane); it weighs more, reducing your useful load and complicating weight and balance; and it has more cylinders and other parts to inspect, repair, and overhaul, resulting in higher ownership costs.
A big engine can also bring a lot of joy: it gives you the option of climbing above problems (icing, turbulence, clouds, mountain waves); it can let you fly faster into a brutal headwind (by trading off some range); it gives you more power for takeoff, reducing distances and increasing your useful load; and most importantly, if your airplane is a radio-controlled model, a grossly overpowered engine allows you to do some pretty neat tricks, as shown in this video on YouTube.
Land and Hold Short 
Sometimes a big engine is a must, especially when flying into mountains, taking off from a shorth (really short) dirt runway
in the mountains (Sierra Madre) at noon in an underpowered aircraft can be really scary. But at the end it all comes to your
mission profile, if paying an extra buck is the price for my safety(and my familys) I will gladly pay it. I live in Sonora,
Mexico.(the state next to Arizona), I own a 73 C182, I like flying into the mountains to small ranches for breakfast(equivalent to the 100
dl hamburger) and my missions include flying to 250-300 miles away contruction sites with 2 or 3 passengers and moderate
luggage, I would never think of doing it in a smaller aircraft. If I want to have a 172, I just pull back on the throttle,
but I always know I have a 182 when I need it.
E. Chavez