Recently, I had the pleasure of flying Turkish air from Istanbul to Athens (fairly short flight).
The plane was an Airbus A320 according to the seatback pamphlet. It was an average medium-size jet (not a jungle jet). Two observations:

What passed for first class was exactly the same as coach - 3 and 3 seats in each row. The only difference was the little curtain defining the "cabin". I don't understand who would pay any extra for this.

But the bizarre thing was that each middle seat (in both 'cabins) was the same size as the window and aisle, which were pretty narrow to begin with, but the space between the armrests of the middle seat could not have been more then 12 inches. No person could possibly fit in these seats, unless perhaps a very young child.
What could possibly be the reasoning behind this?

This is actually the seating configuration in many european "first class" sections. I saw it for the first time on an Aer Lingus flight a few years ago. Maybe someone else can do a better job than I could of explaining how the middle seats end up looking like mini-me seats.

The seats are "convertible" between standard coach and first/business class by moving the armrest position. You saw the latter setting. If more coach rows are needed, the curtain is moved, and the armrests switched to the coach setting for some of those rows.

Here is a link to a recent thread that discusses this in more detail:
http://www.flyertalk.com/forum/showthread.php?t=423891

Generally on short Haul there are 2 types of Premium Cabins

"True" Business Class (Called First Class on most US Airlines)

This is where there is actually a dedicated premium cabin such as Air Canada, American, Continental etc

"Convertible" Business Class

This is on most European Airlines. The move the divider and the seats change between J & Y depending on demand. The middle seat is made smaller and the aisle and window seats bigger to create a 2x3 or 2x2 configuration (depending on the airlines) with a slightly wider seat

It wasn't first class, nor would it have pretended to be. It was shorthaul business class, in a pretty standard European configuration.

Often, convertible sections are already set at a deeper pitch than normal economy. (This is very nice if you're flying economy but sitting in the convertible section. You may have a 3-3 configuration, but it's at business class pitch.) Some convertible seating changes from 3-3 to 2-3 by narrowing the row one side but making the 2 remaining seats wider, and widening the overall width of the row on the other side to make three seats, each wider than the economy seats.

Why would anyone pay extra for this? Usually because the shorthaul business class product is a complete package that includes features like lounge access and decent catering. The wider seat is but one part of the package. Others may have more accurate information about this, but it seems to be generally thought that business class shorthaul pricing within Europe is more realistic than the published first class shorthaul fares in the US, although under severe market pressure at the moment - and it's generally more difficult to get access to the business class cabin other than by paying a business class fare.

Americans of a certain age may remember an arrangement like this in some US airlines' economy cabins back in the pre-deregulation, pre-FF upgrades, pre-business class days. A certain percentage of the 3-3 economy seats (I guess the most forward seats) were constructed so the backs of the middle seats could be folded forward and down, forming a table between the window and aisle seats. I think one airline called it "super coach." Load factors back then weren't what they are today, and businesspeople typically did not fly F. The idea was that if the forward middle seats were the last booked, and therefore likely to be empty, businesspeople would be attracted to a product where they didn't have to sit directly next to anyone and had more room to put drinks and papers. Catering did not differ AFAIK.