You are ignoring cost and engine width.
The width is going to affect both aerodynamics and ground clearance. I4's are the worst in this regard, while twins are the best (unless you count singles).
A great deal of the strengths of configurations actually arise from their limitations. I4's can be tuned for more torque, at the expense of peak power. On the most basic level, its a function of bore vs stroke. There is a theoretical limit to how fast a piston can move up and down. The heavier the piston, the slower its max speed is. In one revolution, the piston goes up the stroke dim's and then down the same distance. Thus the longer the stroke, the faster the piston has to move at any given RPM. Or, the longer the stroke, the lower the red line is going to be. But, the longer the stroke, the farther the distance on the crank shaft, the more of a lever the connecting rod has when turning the shaft, so the more torque the engine produces. This is why sportbikes are oversquare, with bore bigger than stroke, while cruisers are undersquare, with stroke longer than bore.
Since horsepower = [email protected]
* RPM you can either multiply big torque by little rpm, or little torque by lots of rpm. Since at high rpm you can take advantage of a few unique tricks, the winner always tends to be small torque by lots of rpm.
This is why you can build an inline with a good torque spec at the expense of horsepower. Now in the case of twins, you only have two cylinders, to the pistons have to be pretty big. Since they are bigger, they cannot move as fast, so the high rpm is already unreachable, therefor the designers have no choice but to tune them for more torque. If they could get them to spin faster, they would be low torque too.
Let's see, ducati's motogp bike is a v4, and yamaha makes at least one such engine. I believe the honda VFR is a v4 as well. There is also a narrow angle V, as in the honda's V5. It makes for a very compact enigne, that can sport lots of cylinders, and thus have smaller cylinders, spin faster, and make more power.
Now for the costs.
Inline4 are cheap, because there is only one head, with two shafts, and one cylinder block. Twins will be more expensive, since there are two heads to worry about (twice the shafts, bearings, cooling lines, belts/chains, etc) but at least the heads are some what simple. Ditto for the cylinder blocks. With a V4 you have two complex heads and two complex cylinder blocks, so they engine is even more expensive, but it should have the high rev's of an inline with almost the low width of a twin. Narrow angle V5 is more expensive still, but its a motogp bike, so who cares. Angled inline would be the most expensive of all of these, and the least compact.
The compactness of an engine is important, since the engine is the heaviest part of the bike. If you make it compact, you have room to move it within the frame, which greatly affects the bike's center of gravity, and handling. If the engine is large, then there is only one way it will fit, and thats all there is to work with.